I went from film to FX, so my comments are biased. Same angle of view with my lenses, same Depth of Field at a given F-stop.
One thing I didn't see mentioned in this thread is the difference in depth of field at a given f/stop due to the sensor size, circle of confusion and focal length of the lens: DX bodies will approximately 1-stop difference in Depth of Field vs. the same lens on an FX body.
This may be minor to some or it could significant for others...I mean can anyone tell the difference of a image shot at f/2 on an FX or DX body? What about f/2.8? At what point does the DOF difference matter? I'm not sure, as I haven't shot with DX enough to really know.
(What I like about the D800 is pixels on subject...great for cropping and still having excellent resolution; great low light performance, too.)
The excellent low light performance of the D700 works for me and is what sold me on the camera. (Yeah, I guess I could have waited several more months for a D800 but I finally needed to jump in to digital so I did. No regrets on my end with a D700.)