I used a D3 since november 29th and a D700 since a couple of weeks.
After reading quiet a bit of different reactions on different photography gear fora about eventual difference in AF performance between both cameras I did a simple test this morning to check the D700's AF performance using 3D-tracking mode.
My dog was running fast in my direction. And while "images say more than thousand words..." I post here underneath the 4 files.
The lens I used was the 24-70 AF-S @ 70mm.

The four images were shot in less than a second, using AF-C 5fps.

In overall use of my D700 I didn't notice any difference in AF speed between D3 and D700, not with AF-D screw driven lenses and not with AF-S lenses.

I should have used a faster shutter speed to freeze more the action and would have got even sharper results, due to the speed of the running dog, you see some motion blurr right now...

Thanks for looking and kindest regards,

Stany