I had already voted on a 50/2, as I had owned a CV Heliar 50/2 until around a month ago... so, only a Jupiter 50/2 for the Leica... and then, this past weekend, I was on the verge of selling the Leica!
I decided not to, and have decided to go with a 50/1.4 Canon ltm from KEH. Back in the game! And with a 50/1.4 for the first time, not a 50/2!
I think I'd stay with a Summicron 50/2 if I could afford Leica glass as opposed to buying the Summilux; the Canon 50/1.4 that I am purchasing, however, actually has a better reputation than the Canon 50/1.8 in many corners.