This test is very timely for me, as I have just received my copy of this lens, and I am about to leave on a trip that will include photographing wildlife. I am lucky enough to own both a 7D and a 5D III. I assumed I would bring the 7D to use with this lens, but the tests seem to show that would be the wrong choice.
For this question, assume the lens is at 600mm and f8, and the subject would nicely fill the frame (no additional cropping in post) on the 7D. Do these tests show that if I used the 5D III instead, and then cropped the image to be the same size as from the 7D, that the 5D III image would have more resolution and better detail?
I have the 5DIII and 70D, having sold the 7D, and have experience of the Tamron on the 5DIII and 70D. My decision is to use the 5DIII - it works very well with the Tamron in terms of AF and image quality. Even with the sharper 300mm/2.8 II + 2xTC III, the 5DIII in general, but not always, outperformed the 7D and the 5DIII AF is just so much better in consistency.