I may as well call this image Conundrum or Aw cra#. Shortly after buying the D7100 I found myself in a position where I needed the high ISO capability of an FX camera, so I bought a D600. Love the FX sponsor, 8x10 prints up to ISO 6400 look nice. However, the autofocus is a definite step down from the D7100. It's slower to lock on, tracking is not as good regardless of the mode or tracking lock setting. The fact that it's a DX autofocus module means it covers less of the FX frame, and I found that noticeable.
So what I really want is the FX sensor and the better autofocus. D800? But that brings up the next problem I ran into: frame rate. These horses move fast. I can time it so I get the horse rearing up starting the jump or as in this photo going over the top. But the available framemrate of the D600 or D800 won't let me get both. Which would need a D4 or used D3s. Like I said, aw cra#.
Still, the D600 can produce some very very nice images.
Erich