Firstly, may I ask why you bought the D700 in the first place?
As an owner of a D700 myself, I bought it ahead of Nikon introducing its next full frame models (the D4 and D800/E) because I didn't want video to be added to my camera.
Newer models may have advances in technologies but not all may be needed. 12MP of the D700 is more than enough in my opinion. My hard drive is already feeling the strain.
The D700 is a very capable camera & the last without video tacked onto it. This may be a reason to buy another. Also depends on how often and in what conditions the camera is used in (presumably you're buying another in case your existing breaks down).