RS-1 and a AussieMorphic lens; max throw from about 22' or so. Very little vertical or horizontal projector offset. Under those conditions I see no pincushioning at all and the light cone at the AussieMorphic lens is pretty small, about 1"-1-1/2".
The lens does cause a little softening of focus. When I look at the pixel grid while close to the screen, I can see the effect of the lens on the grid lines as they are not as sharp as with the lens in use.
However, I've got no complaints on picture quality. The difference is small. There is a much bigger difference in picture sharpness when going from SD to HD DVDs.