Spell Focus' should provide an effective +1 bonus to the caster level of all spells of its school that do not feature a DC. For example, if someone has Greater Spell Focus: Evocation, and has a caster level of 20, Polar Ray would be cast with a caster level of 22.
Further, benefits derived from these bonus caster levels are not subject to normal caps. For example, if someone managed to have 25 effective caster levels with Polar Ray, and also had Greater Spell Focus: Evocation, it would deal 27d6 damage.
The benefit of this change of course, is that it will make the Spell Focus feat set more consistently useful and applicable.
Discuss.