>D700 Keep in Mind FF cameras make your lens shorter
Though the pther explanations address the fallacy in this statement, from a "non-technical" standpoint, you really should be saying that the DX sensor makes your lenses "longer." If "200mm is really 200m" that's not "shorter" by any possible definition of the word. "200m is really 300m" is "longer."
But again, your focal length never changes, only the crop. You can make a FF with a 1.5x crop easily enough without using the DX mode on the D700. It's called Photoshop
----- This is my Nikon. There are many like it, but this one is mine!