BCalchet
Human, all too human.
Here's another big difference between priests and mages: priests can generally get RoF the turn they're built (or maybe a couple of turns later if you're running peacetime civics). 2 xp, and then you have a RoF caster. Adepts need 10 xp to become a mage. While confessors can be made pretty much combat ready, mages require more of an investment.
I wouldn't call it more of an investment as far as hammers are concerned - you just make that purchase earlier, when building the adept.
Gold, on the other hand, does weigh heavily against the mages. (I'd say the likes of Spring, Whirlwind, Haste, Regeneration, Summon Skeleton and other utility spell do quite a bit to counter this, though - a mage will always have something to do, while a confessor is limited to fighting, providing medic and killing himself building a temple somewhere.)