To the OP, I would say no. Spriests have a fairly long ramp-up for burst right now, and while constant pressure is good spending orbs one at a time will deprive you of burst ability. I view Insanity as a PvE oriented change, you aren't guaranteed the uptime to channel in PvP, especially arenas.
On glyphing- with the MS glyph nerf, I'm now really torn about crit vs. mastery. There doesn't seem to be an answer yet for 5.2