I have a 1986 M6 with a 35mm f1.4 Canadian Summilux, a 50mm f2 Summicron bought new and a 1957 f4 collapsible Elmar. The 35mm suffers badly from coma at f1.4 and at that aperture is very soft. I keep the Elmar un-collapsed or the locking mechanism dosen't work properly. It is sharp OK. The Summicron is no better than my Pentax 50mm f1.4 or 1.7 lenses.
-------------------- Got COMPUTERISED at last and now Digitised but FILM still RULES!