Originally Posted by Dumbledore lives
I think spell focus might be undervalued, because while not a definite pick if I'm at all focusing on one school it can be pretty useful. With this a Gnome illusionist could get even more ridiculous DCs, getting effectively +2 for what used to be +1. I'd say they should both be around +7, but I'm not expert on these kinds of things.
The wonky bit is that Spell Focus's value is dependent upon the school chosen.
Spell Focus - Abjuration and Spell Focus - Divination are kinda junky. (Barring access to a bunch of homebrew or third-party Abjuration or Divination spells that make more use of saves than the current batch.)
Spell Focus - Evocation, Transmutation, Illusion, Enchantment, Necromancy or Conjuration are going to be much more useful, and, even then, Spell Focus - Conjuration seems to be taken 9 out of 10 times as a prereq for Augment Summoning, and not for it's own sake.