I have the versions 1 and 4 Summicron, and the pre-ASPH and ASPH Summiluxes. To start with, forget the pre-ASPH Summilux if you really tend to shoot at f/1.4. The contrast is so low the lens is almost unusable wide open. By f/2 it is as good as a Summicron of the same age. By f/4 you can't tell the difference between it and a Summicron. If you really want f/1.4, you either need the ASPH, or else (hint, hint) the 35mm or 40mm Cosina-Voigtlander Nokton. I use the 40mm. Here's what's good about the 40: it matches the 35mm framelines, at distances greater than 2M or so, of the M7. It matches the 35mm framelines at that distance better than the 35mm lens does. And it costs 1/10 of a Summilux ASPH. and it is sharp!
Both my Version I and version 4 Summicron are sharp, with pleasing rendition; but I probably wouldn't buy them again at today's prices. I don't have the version 3, but it does receive a lot of praise. Oh, by the way: my 35mm f/2.5 Cosina-Voigtlander (CV) is very sharp and contrasty. And it's a third the price of even the version 3. I used it to photograph France with earlier this year; and I'm not sorry! But you wanted something faster. Consider the 35 or 40mm CV!