I had two M-Hexanon lenses, both were very sharp. However, there was an issue with the lenses' focusing cams and my M6 -- wide open and close up they were never quite in focus. Unlike the more expensive Leica M Lenses, the M-Hexanons couldn't be adjusted because of epoxy used in their construction. Others reported no problems. My advice would be to negotiate for a return period and rigorously test with your set up to see whether they meet your needs. When they were "on" they were equal to their Summicron counterparts.