D700 User - Missing some D2X features
What you see in the DX vs FX format for the two cameras is not a function of the format but the pixel density of the sensors in the picture area covered. You don't get additional reach, you're getting greater detail which you then can blow up more. The DX format covers approximately the central 43% of the standard 24x36. The central 43% of a D3x (or an upcoming D700x...) would equivicate to roughly 105 mp in the area covered.