Upload & Sell: Off
I have been playing with some of my old R glass on a D800E and as noted above, some of them like the 35mm Summicron have quite a bit curvature of fileld. I think it is a bit more obvious on a flat/plane sensor as opposed to the slight curve to film.
Of the older 35,50,90, Summicrons, the 50mm Summicron is still top of its class compared to the modern lenses made for digital, such as the Nikon 50mm f1.8 G lenses. Even comparing the 90mm Summicron to the 85mm f1.8 G Nikkor, the Nikkor is sharper across the field, but I think the Summicron produces more pleasant colour and tonality.
I don't have any wide Nikkors yet, but comparing the highly regarded 28mm Elmarit-R, second version with floating elements with the Leica 21-35mm zoom, the prime is probably sharper in the middle, but the zoom stays sharp out to the edges. Probably because the zoom is a more modern design. I haven't done the comparison of the 35mm Summicron to the 21-35mm using the D800E, but I tested them on film a few years back and once again the 21-35mm was the superior lens.
One hint I got from another forum was on a lens like the 28mm where there is a little curvature of field, is to focus using live view on the edge of the frame and let the DOF handle the middle. At f8, the 28mm Elmarit-R is pretty impressive on the D800E using this method. In use, for infinity scenes, I needed to focus just a hair before the infinity stop,
With all this playing around with my R lenses on the D800E, I have decided to keep just the high performers I would use for scenic work and use Nikkor AF for the rest, such as my kids sports. I have sold off my 180mm APOs (f2 and f3.4) and 90mm Summicron, the 28mm is now on Ebay and the 35mm Summicron will probably go to Ebay as well once my Nikon mount for it arrives.
The f5.6 and f8 images from the 28mm using the focus on the edge of frame method are here on skydrive as the full resolution D800E file, converted in LightRoom 4.3RC using the 28mm Elmarit profile.