So, I'm planning to build a undead Chaos army.
Skeleton Chaos Warriors, zombie marauders etc.
However, would it, according to you, be a problem to have 25mm bases on skeletons and zombies? I get the impression there are some advantages and disadvantages, so in the end, it doesn't really matter.

Besides, the rulebook only states "human sized infantry (20mm/25mm bases) = US 1" (or something along those lines). So ruleswise, there doesn't seem to be much of a problem, it's a bit like the 40/50mm monster bases debate.
Just checking to be sure, and "how to avoid problems, if any".