I tend to use back button focus as a preference and have had no issues focussing at all. I have noted since the release of the 6D that many of the issues that people have are user issues and not the camera!!
I have posted superior images to those in the appropriate thread and they were taken with a 6D, I did not post them and try to make a silly point on someone elses post!! But hey if you are happy with them then good luck!!