[Kelly Pedersen]

I concur with the others about not worrying about too much fidelity to the source rules. Down that road lies madness. :-)

That said, I think you can tweak Realm Magic a bit and have it fit Mage: The Awakening pretty well.

First, I'd treat Mana as just a special Energy Reserve (which can only be recharged at Hallows), which is the only thing that can power spells that require mana (no spending FP).

Second, I'd just adapt the Reach mechanic pretty much straight across from MtA: you start with a free Reach for any spell, and each level you have in the Realm above what you need to cast the spell gives another free Reach. Using a Reach changes the parameters of the spell, as per normal. The rules for Reactive Reality (Thaumatology, pp. 193-194) model Paradox pretty well too - just give a die of Distortion Points for every reach past the free one.

I wouldn't worry about Realm Magic being margin-of-success based, frankly. I realize MtA magic isn't, generally, but I think that's really more a matter of rules differences. I don't think it hurts the flavor of the magic if its effectiveness is a on a bit more of a gradient, rather than binary "it succeeds/it succeeds incredibly".

Rotes, I would do by allowing characters who had a Rote to roll the relevant mundane skill as a complementary bonus to the spellcasting roll (possibly giving a bigger bonus than just the standard +1 on a success/+2 on a crit, though).