Field experience with that optic?
I don't own one but just recently I had the opportunity to use the Noctilux-M 50 mm 1:0.95 Asph for half a day. My resumée at the end of the day: Fascinating, and definitely tempting—but not a must, and waaay too expensive for what it has to offer.
For both the special appliances—i. e. 1. capturing low light, and 2. creating thin depth-of-field and ultra-smooth background blur—the Summilux-M 50 mm 1:1.4 Asph works almost just as good. If under poor lighting conditions you can get the shot with f/1 or f/0.95 (which is essentially the same) then in the vast majority of cases you'll be able to get it with f/1.4 also. Shots that you can barely get with f/0.95 but are impossible to get with f/1.4 are extremely rare. And with DOF, it's just the same—at f/0.95 it's extremely narrow but at f/1.4 it's really very narrow, too. After all, the difference between f/1.4 and f/1 numerically is only one f-stop ... and between f/1.4 and f/0.95 is 1.148 f-stops, or approx. 1 + 1/7. Effectively it's even less—more like 2/3 f-stop—due to vignetting.
The vignetting at full aperture is rather strong, albeit significantly less than it used to be in the Noctilux-M 50 mm 1:1. Also the sharpness at full aperture as well as at medium apertures is better than in the older Noctilux. Still, performance at f/1.4, f/2, or f/2.8 does not fully match that of the current 50 mm Summilux Asph, Summicron, and Summarit lenses ... even though some claim otherwise. It's close, but no cigar. So at 'normal' apertures, the Noctilux-M Asph cannot really replace the other 50 mm lenses. The 'regular' 50 mm lenses are drawing with a fine-pointed pen while the Noctilux is painting with a slightly wider brush. For most pictorial applications, that doesn't need to be a disadvantage ... still that's not what I'd pay $10,000+ for.
Size and weight are substantial. The lens barrel obscures maybe 15 - 20 % of the 50 mm frame's area in the viewfinder. That's a lot but somehow you get used to it. Regarding the weight, I wasn't too tired after carrying it around for half a day. After all, I'm used to carry a DSLR with battery grip and telephoto zoom lens, and compared to that, a Leica M with a Noctilux-M Asph still is a lightweight.
It was a fascinating and enlightening (in more than one respect) experience—but I will content to sticking with the Summilux-M 50 mm Asph for the foreseeable future. Maybe when I win the lottery ...
