I keep hearing people complain about the focusing problems with the f/1.4. I guess I have a pretty good copy because mine works superbly when paired with the 5D3.
That said, focus shift is not a problem for me. The f/1.4 comes out only when light levels are real low and I'm shooting wide open most of the time. For reasonable light shooting, I use the 24-70II which is as sharp as anything at 50mm at almost all aperture settings.
5D3, 6D, 600D, RX100
16-35L, 24-70L II, 70-200L II, 100-400L, 50L, 85L II, 135L, 24TSE, 40, 100 macro, 18-55 II, 55-250 II, 600RT x 4
I come here to learn something new, not to learn how bad my gear is - I know that already ;-)!