I have done a short review of how this lens from 1958 performs on a modern digital M240.
http://macfilos.com/photo/2016/5/20/leica-28mm-summaron-f56-little-old-guy-goes-modernperhaps
The output from the lens holds up well despite its age. I am sure that if the lens is 're-issued' by Leica it will be thoroughly modernised.
William