The only disadvantage I see to using a process lens is that it may not be very sharp at its widest aperture. I have a 305 G-Claron in a shutter that is not very sharp at f/9 (maximum aperture), but at f/16-22, it's amazing. This can be a bit of a problem in lighting situations where you want it sharp at f/9 or f/11 and it ain't quite there.

Peter Gomena