Well, the D800 has returned from its 3rd service. This service was mediated through a service mgr (not the director, although she appointed him to contact me directly). It seems that Nikon still cannot find any significant abnormality in the focusing system, although my contact does admit that my images do show definite front focusing problems at the center point when the left point is correct. There was a bit of weaseling (sometimes the focusing is not accurate in poor lighting, I should use only the lenses recommended for the D800, etc. etc.) but he did realize my frustration and could see my point. They did do some "tweaking" before return, but I have not been able to test fully using the protocol that he himself suggests (it's a good one) because I'm away. Since I did take the D800 with me, I was able to shoot about 100+ images using the center focus point, AF-S. I must admit that they look awful good, sharp, great color - all you could ask for - so the camera is certainly usable but, for now, only at the center point.
When I get the chance to retest next week using the requested protocol, we'll see how things shape up. For now, I can only review the 9 pages of emails we sent to each other and take some more images.
The end of the story approaches....but the ending remains in doubt.