I have a D700 and a D800 and I use them both in tandem. To get the best out of the D800, I believe one has to use perfect technique and the best lenses you can afford. Consequently, I use the D800 mainly with a tripod and Zeiss zf primes. I find that even very good lenses like the Nikon 24-70 show their limitation with the D800.
The results I am getting with the D700 and the D800 are pretty close for most lenses, especially when using smaller apertures. I use the D700 for more casual photography and travel.