The one change Dom2 really needs.....

[Chazar]

I would also dislike it if forging requirements diverge from forging costs, but its probably better for balancing though...

Arryn said:
IMO, what makes Caelum so strong isn't that their units fly (...), but that they have a large air income to spend on equipping non-air SCs or summoning those air queens that you mention.

I've played Caelum quite a bit, and even with GaleGate up early on, you will never ever have enough air gems to supply all your mages with the gems the burn in every battle, not counting the obligatory StaffofStorms in every skirmish-group and those BagofWinds,etc. I found it easier to summon IceDevils with the Blood-sages I get than summoning AirQueens. The mobility, however, is a large boon, as your armies can always be kept busy and thus worth their cost & upkeep. It was the key to my success in a game against three allied opponents on the small Urgaia map, since I could use the same forces again and again to push them back in a round robin fashion as they were poorly coordinated (was sort of a introductory game for my friends ).
So I also guess that flying/teleporting is essential for SCs, because that is the reason why they can easily outrun any substantial no-SC invading forces; disabling the strategy to hit a big empire at different corners...