There's a speculation over on CR about a new firmware being expected that might improve AF performance; of course that's CR, so let's not hold our breath until it's posted here in the News section, but perhaps Canon will do something to catch up...
+1, You should wait and see if the firmware really improves the AF performance.
Canon 5D Mk II, 550D/T2i, 50mm f/1.4 USM, 100mm f/2.8 L USM, 17-40mm f/4 L USM, 24-105mm f/4 L USM, 70-200mm f/4 L IS USM, 320EX speedlite