[shuttertalk]

It's unrelated, but I've gone through most of my lenses for AF tuning, using the centre point, and found that three of the four needed a slight adjustment (5-10 points) in the same direction. I tried that once with my D700, but couldn't see any difference in the focusing results – probably not enough resolution to see the differences.

You know that's exactly what I tried to do with my 7D as well but after micro adjusting back and forth I couldn't tell the difference and just left it at 0.