I am really tored apart of the last month. I am trying to decide which FF camera to upgrade too. I`ve been using an Canon T2i for the past 4 years and I`ve been doing more and more photography. So of course, the most logical upgrade for me is the Mark III but there is a few feature I like about the D800 that his holding me back :
1. FX -- DX crop mode
2. Higher dynamic range
3. 600$ cheaper
If I go with a Mark III, I would have to sell my Tamron 17-50mm non-vc/Canon 55-250mm and get something like a 24-70 F2.8. I am sure there is lots of users in my situation that are pondering the same decision.