I've been rocking a 5DC since launch, and have never been happy about having to manually focus on anything outside of the center cross AF point with pretty much any of my fast primes wide open (e.g. 50L, 85L II, 135L).
The high precision, MF screen helps and is a life saver, but it's become a crutch as I've come rely on that to validate all focussing. That said, the new 5D III does not have user replaceable screens allowing for proper DOF previews for lenses faster than 2.8
For folks shooting primarily fast primes with their 5D III, how are you coping with this? Is the AF capable enough so that focus points on the edges are accurate down to f1.2?
Focus and recompose is not an option for me. The focal plane is in the millimeters at f1.2 for tighter portraits