Well, having ALL the FL lenses in superfast versions is missing the point. In practice, I find that a fast 35mm lens for really low light photography pays off. I've had the original Nokton 35/1.2 for a long time before selling it to a friend who REALLY WANTED IT, and now I'm using the 28 Summicron as a substitute, but still think of getting a 28/1.4 or 35/1.4 next time I will really feel like I need to shoot in low light. Another type of fast lens which is good to have, is a portrait lens. It can be a 50-60mm range or 80-90mm range, and in this case I prefer SLR lenses over RF, although the RF Summilux 50 pre asph is a lovely portrait lens for sure. My picks would be Pentax 50/1.2, Olympus 55/1.2 or Minolta 58/1.2 for the shorter range, and Summilux 80/1.4 for the longer range. Yes, I know there are some sharper lenses available now, and I still think every now and then about the Noctilux f1.0, but as said above, wanting the very best over a very good is detrimental to your bank account. For everything else, lenses like the above mentioned 35/2.8 Summaron, 50/2.8 Elmar v2 or the 90/2.8 Elmarit R are far more practical.
