That 6D image isn't remotely close to the actual spread on the camera. It's far tighter and more centered than that.
Here is the 6D AF point array set within the entire frame.
TY Neuro...I knew the image i found was off...shouldn't have even posted it.
Either way - as with all things in photography there is a give and take, you give up this and gain that.
I very much enjoy shots where the subject is set to the far left or right, and depending on the DOF i want, I focus recompose or shoot wider and crop.
I have worked with the little XSI, the 7d, the 5d2, 6d, and 5d3. And in post process, my second shooters have used all of what I have and - a 5d Classic, a 1d3s, a t series, and I am just starting to take a look at files from a nikon d3 and a d4. Give and take, above 1600 ISO the 6d, 5d3, d3 and d4 take the cake! The 1d3s files were gorgeous! But, the best that I saw from that body was at the ceremony and the formals. At the reception, good but he had to use heavy flash to get the shots so while they are good, the ambient light is pretty much lost. And as to the 7d - I used that body for 2 years, but after picking up the 5d3, even the extra range didn't matter because at the ISO ranges I typically work in (above 1600), the 5d files cropped looked better than the 7d's uncropped. So far what I see from the 6d is pretty awesome, the files are on par with the mk3. Give and take, I'll gladly give up a few points of AF for that!