The launch of the 5D3 and 6D were exciting and I saved up funds to make the switch from my 5D2 to a 5D3 or 6D. Now that I have the money, as I pondered my options, studying my shots over the last year or so, I find that I am not held back by the 5D2's ISO limitations but could really benefit from better AF on the long end (e.g., birds, planes, hot air balloons, etc.).
I decided to keep my 5D2 and purchase a 7D as a base for my 100-400, 70-200 w/TC, 100L (macro). I believed the 7D AF, while not as advanced as the 5D3, will meet my needs, and I'll benefit from the reach advantage of the crop.
Am I missing something?
Some background: My 5D2 mostly hosts a 17mm, 24mm or 16-35mm (mostly landscape). I use a 35, 85 and 70-200 for shooting people (with tripod and flash setup, I don't need to push the ISO). I fall short when shooting long. The 5D2 just isn't it. Both AF and reach fall short. I have a T2i to cover the reach, but it's focus is not as accurate as the 5D2.
I'm looking for affirmation that I'm heading in the right direction (keeping the 5D2 and adding a 7D) or counter points from folks who have been here and back (a 5D3/6D is required