I have been considering trying a Voigtlander in the 35mm-50mm range. In particular I was considering the 40mm as well as this 50mm. I don't know if anyone here has compared these lenses or in specific used the 40mm and can report on the experience.I was going to mention this lens! I bought it several months ago and it is the most amazing lens I've ever owned. Taking portraits of people at f1 gives fantastic results. As for night photography you can use it under any conditions and have relatively low ISO. I started out with AF lens in the '90's and had never used a manual lens until now. There is something very satisfying about focusing on a very fine piece of machinery. There are some tricks to focus quickly if you are trying for people shots in the street--use peak focusing and have the focus magnification option set to 50% to insure sharp eyes.
I am a big fan of super sharp primes with creamy dreamy pokey.