I have got almost not optically damaged Summar and Summarit. Just have to clean layer of smudge from one and kill one small fungus spot on the other. They were without scratches on lenses. I went from first 50mm Cron to all versions up to four. I had other old and not so Leitz lenses. I used them for at least on year and took hundreds of all kinds of photos with them. Sold and no regrets.
Right know I have Summarit-M 35 2.5 which I purchased new at discount price, because it is not popular lens for status and show ups. This is the only Leica lens I'm finding worth to keep because price, performance, size and build are optimum for me.
I also have version III Cron 50, I traded for IV which has plastic aperture parts and this one is stuck in sale on discounted price because among clueless Leica snobs it is bashed as bad lens. Version III Cron is just as good as IV, made with all metal, no plastic, but among Leica snobs been clueless is part of the club. They are repeating same mantras and myths without looking at images and comparing to other lenses.