This is kind of what I have been blabbing my LS's ear off for the last few days with. The example I used was something like this.

CON (WHM/BLM): WHM: x2 Spell Cost Reduction of Healing/Buffing spells, Enimty Reduced while casting said spells. Offensive spells x2 cost. Vice versa for BLM.

THM (RDM/ARCANIST): Refresh/increased Acc with Debuffs/Potency. *Arcanist* Speculation~

GLAD (PLD/???Something Offensive): Def+ Atk- Increase Healing potential, Buffs str increased def.

And so on with MRD being DRK/WAR, RNG being ARC/MSK, LNC being DRG/SAM, PUG being THF/MNK

Now of course this leave out files that were data mined in Beta; for example: Assassin, or the "whip" user. Anyways, I really hope it turns out something like this.