My 6D shows tomorrow and I'll do some testing and post. One thing I will test for that I haven't seen elsewhere is the "in focus range size".
Here's what I mean... When testing my 50D and 5D2 I found an interesting phenomenon when trying to dial in the AFMA for an autofocus confirm chip on my manual focus Rokinon aka Samyang 35mm (nice lens BTW). It mattered whether I was focusing from infinity to closer in, or from close in to further out when shooting a test target at a fixed distance.
My first thought was "well, we just discovered the 'cheap' part of this lens" and the first thought was there is play in the internal workings of the lens. But upon digging in a bit more, I discovered this phenomenon was very pronounced on the 50D and much less so on the 5D2.
So then I start thinking it has something to do with the body rather than the lens. So I test the 100L and get essentially the same results manually focusing it while using AF confirm. The conclusion being it is in fact an issue with the bodies and not the lenses.
While using manual focus plus AF confirm with either lens, I was able to determine the 50D had a fairly significant range of focus in which it would confirm with a beep and a red indicator. Meaning if I slowly focused from infinity 'inward', it would confirm (after best effort AFMA adjustment) while about 4 'AFMA clicks' back focused. And if I slowly focused from min to 'outward' it would confirm about 3 'AFMA clicks' front focused. And this was true with either the Rokinon or the 100L on the 50D.
So same test on the 5D2 and the "range of in focus" was probably 1/4 that of the 50D (a good thing). Which explained alot of unpleasant things I experienced shooting the 50D at very shallow DOF (hit, miss, hit, miss)...
So anyway, I'll do the same test on 6D and post results.