I don't really see the upgrade path from 7D to the 6D.
The 7D has the higher frame rate for action, the AF seldom fails and the pixel count not all that different. I have absolutely no problem with the image quality, and that is using such greats lens as a 24-105L, a 28mm f2 Zeiss Distagon, a 35mm PC Distagon, an 85 f/1.2 Zeiss 50th Anniversary and a 200mm f/1.8 Canon USM
One place where the rubber meets the road in the superior build quality (seals, dial layout esp) over the 6D.
I viewed the 6D as a sort of inexpensive test camera for the FF market. and after handling it and using it for a day, my thoughts haven't changed in that regard. It felt sort of toyish, and the 20M pixel count was sort of underwhelming.