As it appears that a lot of knowledgeable people are following this post, I would like to ask another question.
Your crop's with the D7000 have considerably more pixels than either FX cameras. Although pixels are more compressed on a DX sensor I would have expected sharper images with the D7000.
I am under the impression that one of the major "benefits" of a DX body is the "Crop factor" for reach. This obviously helps on the long end where you get an extra 50% reach with that expensive glass.
If your results are reproducible why would any pro wildlife shooter use DX? They could always just crop there image with an FX camera and still get superior results.
Something just does not sit right with me with these results and I wonder if others who have both FX and DX bodies are able to just crop there FX images and get better than comparable results to their DX bodies.
Sorry I could not add anything and did not mean to steal your post.
"Cameras and lenses are simply tools to place our unique vision on film. Concentrate on equipment and you'll take technically good photographs. Concentrate on seeing the light's magic colors and your images will stir the soul." Jack Dykinga