I was told that the dev's don't monitor the Slitherine forums, and I need to go on steam to get my voice heard. Hence I did not buy. If you feel strongly enough about it, go to the steam forums.
Have you tried Advanced Tactics Gold? I know it is a bit dated now when it comes to GUI and such, but you can create almost anything in it, with its scenario editor. Matrix sells it, and it is on Steam too.
There is the obvious difference that Steam is cheaper than the Matrix/Slitherine. That also means that the developer gets less "pocket change", since lower price means lower income. However Steam provides a bigger exposure to the developers game, hence more sales. Steam also takes a piece ...
I keep coming back here, just to check if there is an update of some sort. I am disappointed each time. I don't mind the game not being published (at least not yet) but I would like to know the status of it...