I love my Nikon D800 for sports. However, my D700 maintains a very useful place as a tool for my sports photography. The advantage the D700 has over the D800 is its ability to shoot at 8 fps with the vertical grip attached (with larger capacity battery). The ability to capture a photo like this is only possible by capturing the action in quick succession.
Shot with D700 and 70-200mm f/2.8 VR lens, with 1.4x extender attached