In response to the "power creep": you're right that Psion is a more powerful feat than silent spell, still spell, and eschew materials put together, but I think that the balance can still be maintained. Feats for spellcasters in AU are inordinately more useful than magic feats in 3.0/3.5, there are a wide variety of templates, more than anybody could possibly take, and then we haven't even broached the exotic spell, unique spell, and complex spell feats.
This also fits in that spellcasters have a lot more flexibility in how they cast their spells (heightening, diminishing, adding spell templates, fusing spell slots up and down, and so on, added on top of the flexibility of a sorceror).
The balance is that spells seem individually less powerful: in its normal version, eldritch armor (+4 armor class: 1 hr/level, aka mage armor), is an exotic spell, meaning that you have to spend a feat to get it.
Sure, lesser battle healing is simple, which means all casters get it, but as a 2nd-level spell, it's 1d6 + level healing (max 10 I think).
So, to sum up, feat power for spellcasters has gone up, flexibility has gone up, but individual spell power has gone down. I like that feel, but your mileage may vary.
