Anyone who is concerned about autofocus performance should read this article by Roger Cicala:
It tells us why the autofocus performance of the 5D III and the 1DX are so superior to previous models. It's not just more cross-type sensors. Briefly, Canon has finally gone to a true closed loop system. Previous autofocus systems are now obsolete for serious work, in my opinion, and it's about time! I am so sick of messing around with inaccurate and unpredictable autofocus. Having to send lenses and bodies in for focus calibration all the time is ridiculous.
Who knows which system the rumored 6D will get? I know I will wait to find out before I make my next FF purchase. I don't need many of the features the 5D III offers, but I must have that autofocus system! LOL
Would be nice to add 5Diii AF to it. Doubt it, though. So: 5D3 then...