Fundimental Balance Change to Capture.

[Blade0]

I like it a lot.

Well, that is good, because this is the perfect game for you!

For me it would be better without the slot limits. Still, you have a point that we need to model the availability of equipment (and men) as well.
For that what I would do is convert all "normal" equipment to "prototype equipment". I mean that normal equipment would arrive to a pool just like prototypes, but not ahead of normal historical time. This represent a pool all generals are getting supplied from - you are spending your prestige to take your pick. This also forces you to plan reinforcements ahead - if you lose equipment on the field, then you must deal with it till the battle ends, or think ahead and keep some reserves.
Then the next scenario you have the pool again, which is refreshed - units no longer produced will get out of stock eventually, and as other generals supply from this pool too, some of the more advanced equipment you haven't picked can become short supply as well.
This forces you to "fight with whatever your country can give you", think ahead or deal with the losses, and produce a more historical setup without taking away your reward for being clever and win more/avoid losses.

I don't want to put together the whole concept - I am powerless to build it all (because of the lack of modding support), and I am sure the devs have their own ideas. But I would certainly touch prestige - and start with economic concepts about how inflation works in this case. Because it is either inflation of prestige, or a PzIIC should cost way less in 1943 compared to 1939. And no, capping the prestige gain is like taking candy from the baby.

[Horseman]

I like it a lot.

Well, that is good, because this is the perfect game for you!

For me it would be better without the slot limits. Still, you have a point that we need to model the availability of equipment (and men) as well.
For that what I would do is convert all "normal" equipment to "prototype equipment". I mean that normal equipment would arrive to a pool just like prototypes, but not ahead of normal historical time. This represent a pool all generals are getting supplied from - you are spending your prestige to take your pick. This also forces you to plan reinforcements ahead - if you lose equipment on the field, then you must deal with it till the battle ends, or think ahead and keep some reserves.
Then the next scenario you have the pool again, which is refreshed - units no longer produced will get out of stock eventually, and as other generals supply from this pool too, some of the more advanced equipment you haven't picked can become short supply as well.
This forces you to "fight with whatever your country can give you", think ahead or deal with the losses, and produce a more historical setup without taking away your reward for being clever and win more/avoid losses.

I don't want to put together the whole concept - I am powerless to build it all (because of the lack of modding support), and I am sure the devs have their own ideas. But I would certainly touch prestige - and start with economic concepts about how inflation works in this case. Because it is either inflation of prestige, or a PzIIC should cost way less in 1943 compared to 1939. And no, capping the prestige gain is like taking candy from the baby.

I wouldn't say its perfect (but then what game is?)

But actually what similar game allows an unlimited number of units? I'm hard pressed to think of any.

Your idea of having limited amounts of equipment is an interesting one and not one I'd dismiss out of hand. But lets remember its not about making it perfect for me or for you its about making it "perfect" for as many players as possible - part of that is in allowing choice.

As its stands I can choose to make a small elite force. All the latest and greatest tech, over strength all around. Wouldn't have many units but would be a compact lean fighting machine.
I can also choose to have a huge army of infantry, older tanks and aircraft. And of course I can choose to build a core anywhere in between these two extremes.

If your (still a good) idea of limiting all the unit types as the prototype system works now was implemented then it would remove one of those options. Or if it didn;t remove that option then it would basically have no impact.

Of course we could go back to the PC1 way of one unit = one slot. Then your idea could work to limit having ridiculous amounts of top tier equipment. But that still leaves the issue of removing an option (having a small core of elite units) As has been stated more than once and not just by myself - choices are good and help make the game better for everyone.

If you're interested in testing your idea then actually it would be rather strait forward.

Either use the editor to raise the unit cap on every map to such large numbers that unit cap no longer matters or mod the units file to reduce every German unit to cost 1 slot (o slots might work but I'm not sure) Don't forget to alter the half tracks to not cost too. (Or you could do both)

You could also edit the rules file to make it so that OS does not cost any additional slots - I'd have to go and check to see if you could also mod the prestige cost.

[Blade0]

Either use the editor to raise the unit cap on every map to such large numbers that unit cap no longer matters or mod the units file to reduce every German unit to cost 1 slot (o slots might work but I'm not sure) Don't forget to alter the half tracks to not cost too. (Or you could do both)

You could also edit the rules file to make it so that OS does not cost any additional slots - I'd have to go and check to see if you could also mod the prestige cost.

Er, I have already tested this before posting. It is easier - just set "slots" column in the equipment file to 0 in all rows. Voila!
I have actually tried a play-through with modified slots - I did some modifications which I felt more just, based more on production and real life availability. It didn't work that well - I felt that while I improved something, I am not solving the right problem.

My point is NOT giving the player unlimited resources. My point is to limit this by only one factor instead of two - namely prestige.
The argument behind it is that prestige is currently broken. So the main limiting factor is "slots", which I feel very artificial (no real-life justification behind it), and a source of constant "min-maxing" to get the most out of the current limit. Moreover, my performance in the battle has absolutely no effect on the number of slots I am getting, so I just hate to play, and try to pass the scenarios as fast as possible, as for the next one I am guaranteed to get more slots and newer equipment.
I think that prestige can be fixed, and it should be, as it is a way better measure on my performance than slots.

[Horseman]

Either use the editor to raise the unit cap on every map to such large numbers that unit cap no longer matters or mod the units file to reduce every German unit to cost 1 slot (o slots might work but I'm not sure) Don't forget to alter the half tracks to not cost too. (Or you could do both)

You could also edit the rules file to make it so that OS does not cost any additional slots - I'd have to go and check to see if you could also mod the prestige cost.

Er, I have already tested this before posting. It is easier - just set "slots" column in the equipment file to 0 in all rows. Voila!
I have actually tried a play-through with modified slots - I did some modifications which I felt more just, based more on production and real life availability. It didn't work that well - I felt that while I improved something, I am not solving the right problem.

My point is NOT giving the player unlimited resources. My point is to limit this by only one factor instead of two - namely prestige.
The argument behind it is that prestige is currently broken. So the main limiting factor is "slots", which I feel very artificial (no real-life justification behind it), and a source of constant "min-maxing" to get the most out of the current limit. Moreover, my performance in the battle has absolutely no effect on the number of slots I am getting, so I just hate to play, and try to pass the scenarios as fast as possible, as for the next one I am guaranteed to get more slots and newer equipment.
I think that prestige can be fixed, and it should be, as it is a way better measure on my performance than slots.

Good to know the setting slots to zero works - I wasn't sure if that would break something (been too busy with Defenders of the Reich to test)

It is an interesting concept for sure - there would certainly come a time when more units would just not help (only so many can fight at a time)

One question - how did you control OS? With no slot limit there's no disadvantage to OS on everything and it becomes very cost efficient to just OS everything. (you take less damage so have less cost to replace etc.)

The other issue that would need to be addressed is balance.

Its almost impossible to correctly balance a campaign like this to be suitable for a full range of skill sets. Having a slot system in place help to rein in the more skilled players (it doesn't mater how much prestige you earn, your core is still limited) But with no unit cap how would you go about balancing to keep it a challenge for skilled players without it being too hard for the less skilled?

[Blade0]

Good to know the setting slots to zero works - I wasn't sure if that would break something (been too busy with Defenders of the Reich to test)

It is an interesting concept for sure - there would certainly come a time when more units would just not help (only so many can fight at a time)

One question - how did you control OS? With no slot limit there's no disadvantage to OS on everything and it becomes very cost efficient to just OS everything. (you take less damage so have less cost to replace etc.)

The other issue that would need to be addressed is balance.

Its almost impossible to correctly balance a campaign like this to be suitable for a full range of skill sets. Having a slot system in place help to rein in the more skilled players (it doesn't mater how much prestige you earn, your core is still limited) But with no unit cap how would you go about balancing to keep it a challenge for skilled players without it being too hard for the less skilled?

For OS, even PG had a system that made overstrength more expensive. The rules of PC1 are here:
https://panzercorps.gamepedia.com/Prestige
This has changed in PC2, and I would be surprised if this weren't controlled by some config file that is changeable.

As for balance, it has to be provided regardless to using slots, prestige, or both.
My argument is that in the current gameplay, prestige is not a factor at all (too easy to get), so the only real constraint is slots.
Now slots are invariant. They're carved in stone - if you enter this scenario, you get N slots, regardless of how well or poorly you have played. The only thing you're really carrying over is the experience of your units.
This is what is bothering me - the game is not rewarding for doing well. The game is not rewarding me for not suffering losses - I can just press "elite replacements" and nothing happened. The game is not rewarding me for doing more - finishing the scenario early, or capturing additional targets. Hell, I can't even "keep" the units I capture - because of some God-dictated "slot limit"! Nothing helps, my performance only matters if I suck, and lose more prestige than I earn...
Slot balance is also far from being perfect. I had no problems with the progression of #slots I get, but the relative slot consumption of units is frustrating many places. It is typical that for +10% performance you need to pay 1 or 2 extra slots, which kinda removes the smile from your face when you see the new equipment available. I have mentioned the change from PzIVF to PzIVF-2 - Guderian was insisting on this change from the invasion of Poland, and Hitler personally requested the longer barrel guns, but ordnance just ignored this idea till 1941 - by the time they actually completed the upgrade, late 1941, Barbarossa has mired down partly because of the ineffectiveness of the "stubs" against Soviet armor.
And when you finally get the upgrade available at '42, you notice that they cost DOUBLE! So, what can you do? You can either retire half your tank force, or keep using stubs! You can maybe get one for your lead hero tank, from the increase of slots between scenarios, but that's it! My 1st play-through I marched through the US and half my tanks still had stubs!
On my second play-trough I tried to balance it out a bit - based slots on chassis and role, ended up with something a tad better but still off. Then I have realized that the complexity is just too high for a human to solve, and discarded the idea of slots altogether.

So, no slots please. Prestige is simple enough to balance, it is really up to you what to use. If supply can also be defined somehow, the better. Otherwise, it is up to you to decide how to turn prestige into equipment - there is no one perfect solution, but some strategies will work better than others.
But for this to work, prestige needs to be controlled better. No prestige for capturing. Overstrength costs more. Inflate prestige or equipment costs properly (another topic I haven't mentioned yet).