Alright, since I haven't really gotten a lot of feedback but what I have gotten indicates they should be stronger, the archmages will generally see a 3 point channeling bump, an additional 1/6 health, more fiddling with armor and base melee, and they'll be level 12.
Ideas for mages aren't as cemented at this point as they were when I started the thread, but here's a thought or two.
The Oceanid and Dryad get folded together to make the Nymph. She'll have nature, water, and songs in-school. She's representing the idea of magic as a natural concept, and should have abilities in line with that. Fire and War are triple since they aren't really concepts that work well with it.
Warlord, priest/ess, and High marshall all combine into the High Marshall. This mage will have training in all holy, and all war. He will pay triple for mind and darkness, being a martial master and unfamiliar with curses or telekinetic tricks.
The Lich will combine lightly with the enchanter and the archon. He'll have full darkness training, will count as a mind mage for psychic spells, and training in metamagic. He'll be playing the part of the wizard that dabbled in dark magic and 'ascended'. Paying triple for nature and holy is just good sense.
The Cambion will be combining with the larger half of the Archon to make the Archdemon (unoriginal name, I know, but it is a clearly defined position within demonology). He will have training in darkness, fire, and force spells. I'm thinking he will have excellent stats up front, but maybe unable to use some types of equipment. Expect his opening attack and armor to mirror Adramelech a fair bit, so maybe he doesn't need the equipment. Holy and water will cost triple. No real avoiding the undead and demonic mages hating holy.
Lord of beasts will not be combining with anything. He's just expanding a little bit. He will have the Nature school and training in animal and command spells. This is just a small buff, really. More will be put into the mage's abilities than anything. Still fire triple.
Final archmage will be a return of the Archon to the Sage idea. The Sage will be trained in non-creature arcane, mind, and clerics. This gives him quite a nice toolbox up front. Expect this mage to have some resilience to it.
Gonna take a while to reimagine everything. Be back with more later.