Thanks for the tip. Will try live view next. I have not yet set up the AF corrections for my lenses on the D800
I did also shoot wider apertures (f5) and assessed all at about 1/2 way out from centre. Even at f5, the anti-vibration effect showed up far stronger than lens variations.
It was telling that the 18-200VR, which I always regarded as not very sharp, gave a sharper looking result with mirror-up release mode than the famously sharp 105VR macro in normal release mode on both cameras.
BTW the subject of the tests was bamboo fronds at about 75 metres against a bright but overcast sky.