you're not going to lose them in a hurry at least.
"da plan" here is simply to get some painted and see how it looks, I've got some 30mm and 40mm deep bases (wrong width though) from other things to experiment with. To me it needs to look good and fit in with game definitions to make telling unit types apart quick and easy.
All my units are sized for three ranks in terms of model count it appears (typically 36 - 40 models per unit), though I'm planning on having them a bit closer together than you've shown there. It looked ok on 40mm deep bases, have yet to try on 30mm though