I think that a Summicron 50mm of any vintage should be a very satisfactory lens. The only reservation I would have with the collaspible model would be to see that it is still accurately focussing. Although I have not experienced myself I have read that they can need maintenance to have correct focus. Try focussing on a near object and exposing at f2 to see if the point of focus on the negative agrees with the point chosen.

Enjoy your new lens!