Slitherine

Would there a big game impact if I based my HI on 20mm deep bases?

I've played a bit of DBx, and there was always a 'geometry' problem calculating flank attacks on close order foot, due to the fact the bases were 40mm wide but 15mm deep - they didn't line and very fiddly.

If I'm starting anew with FoG, I'd like to avoid this if possible. Now that I think about it, how about mounted on 40mm deep bases? Would this distort the game? Would I be barred from tournaments?

Base depth has a lot less impact on FoG than it does in DBM and the rules specifically mention that the use of non-standard base depths is allowed.

IMO 20mm deep HF and 40mm deep mounted should be OK with one caveat for the HF in that it is OK as long as they cannot be confused with any MF in the army by your opponent.

The only real case where it makes a difference is in stepping forward when charging and this can be mitigated if you only allow bases to step forward the nominally correct base depth.