Very sure on all counts. I have used a laser alignment tool and also get pin sharp image corners with the 105 rodagon at 20x16 and up, presumably due to the large IC (wide open at f5.6). I also get pin sharp images with the 50mm up to 16x12

With the 50mm lens I own, the images are tack sharp in the centre and top, bottom and edges. Its just the extreme corners the suffer and only at large sizes at wider apertures. At f8-11 the corners are pin sharp at 20x16 and up, but the times too long. With the 105 rodagon I get better corners on a 20 x 16 wide open than I do at f8 on the 50mm lens at the same print size.

The negs are pin sharp and I judge everything by the grain in any case not the image. I use double glass carriers. 6x7 negs printed to 20x24 also pin sharp using the 105 rodagon wide open.