Upload & Sell: Off
You need to look up the Thom Hogan Article comparing the D700 to the D3. It lays out from almost every angle what the real difference is.
Found it here:
Also, the D3S is a newer camera, so it's worth more. For the next few years, it will stay that way, though both of them will drop in price. Oh, it's also about a stop better in noise.
On another note, I have seen several people asking to swap a D3 for a D700 over the last few weeks. Although I can't recall where.