I'm considering picking up a Nikon D3200 for telephoto use. I find it's pretty comparable in price to buying a teleconverter (if I shop around) being the 1.5x crop factor. There is the added advantage of being another camera, so I have a backup body and it's much lighter than the D800. The disadvantage I see is the slower AF performance and perhaps issues with tracking especially for wildlife? Not really worried about lack of certain features like effects and such; or the lack of a AF motor screw. Any thoughts on this?