The only thing I'd worry about is that Wizard become the only real choice for Arcane casters due to this boost. It's hard to ignore a +2 to spell DC when choosing your class. But considering the low number of A
Again, I don't really understand why they moved away from "X monster is worth Y exp" and moved to a much more complicated "calculate the party level, then calculate the level of the encounter, THEN decide how much exp it's worth for the median PC level, but you have to adjust that...