I have a Nokton, I bought it becuase it came in at a great price and I had th emoney and intended to flog it again, but 6 months later I still have it. I pitched it against a PreASPH 50 Summilux and was very surprised to find out that it improves on it for general photography, matches it in lowlight and a slightly behind -not noticeable- on actual tests fr color rendidtion and shrpness wide open. Stop it down to f4 and the Nokton nudges ahead. Its a nice lens, very smooth feel, short throw, lighter then the Summilux, but not skimping on the finesse.
I believe that the Ultron 28, 35 and this Nokton are the best lenses CV have, both in terms of design, build and result. Nice oof areas with 11 diaphragm blades.
Id really like to try a colapsable heliar for the sheer hell of it, I love that Leica varsion but its a little slow for my tastes.