If you are gonna burn a feat on anything, Arcane Mastery is about your best bang/buck buy. The ability to take 10 on ALL CL checks is pretty clutch. Its not just overcoming SR, but also Dispel checks and opposed CL checks for various sundry spells and abilities. My DM let me take a divine version for my counterspeller cleric, and between that, the Inquisition domain, and Divine Defiance, he's kicking some serious spellcaster booty. I think Incantatrix has a few tricks that are CL dependent, so that might help.