I have the old 50/4 Distagon for my Rolleiflex SL66 (same as Hasselblad) and once stopped down to f8 or f11 the performance really convinced me. I did not expect it to be that good. At f4 and f5,6 it is softer, especially when used for close ups. Used in the 1m range at full aperture it is very soft! Superbly sharp and contrasty if used at f8 or f11 at wider distance. I found it even better than my 80/2,8 for that. I was also amazed about the high contrast and colour saturation though mine is only single coated.
Have a look on my Gallery, there are some pictures taken with it.