Nikon D700 and D810

Again if you look for scientific analysis this is not the place.  The below is a matter of opinion from an amateur shooter.

AF-C is important to me, I want fast accurate focus tracking.  On paper the D810 seems or actually states that it is using the same AF as the D4, which I assume is superb.  I don't own a D4 or D4s, but being a flagship or the last flagship camera, I can just assume it's superb, right?

My experience with the D810 is that, the AF is accurate but AF tracking is not so hot.  In comparison, the D700 seems track better at least when I am using the D9 or dynamic 9 points at shutter priority.  I tried the Group Focus in D810 and it isn't that hot either.  The D700 files just look sharper, cleaner and more in focus in most of the time than the D810.  It's not that I don't have any good files from the D810 but there is something about the D700 that I like.  The files are smaller, the processing time is shorter, images look sharper from NEF to JPEG ...

Again further shooting is needed to re judge the camera.

I got the D700 in early 2015 and the D810 in early 2016.  The same AF-S 70-200 VR is mounted.