If you want to use F1.0 or even F1.8 wide open with the Leica M system using 100-400 ASA, then ND and/or polarizers are going to be part of the equation. I use the B+W 8x ND filter with Noctilux 50 1.0 with ASA 100-400 all the time. I sometimes also use a B+W polarizer when I need to cut back on the light a little. I recently picked up a B+W polarizer for the Voigtlander 28 1.9 ASPH after unsuccessfully trying to track down a B+W ND in 49 mm for that lens. I also use a 72 mm Nikon polarizer on my Nikkor 28 1.4 AF-D a majority of the time on my D3 during the day in order to use that lens wide open.
While I have never "liked" using filters on lenses, I have and will continue to use ND and a polarizer on my fast glass in order to use it wide open. Until they bring back 25 ASA colour film, there is no choice if you want to use F1.0 or even 1.8 wide open with Leica M film cameras.
It's funny but one of the only reasons I really wanted an M9 was the faster shutter speed with this camera. After waiting this long and still not being able to get a camera from my dealer, they can keep their M9. Especially since I've got my eye on a black MP to go with my M3/M6/M7. My M3 needs some work and is going in this week. Film is cheap 😛. Waiting for Leica to make me an M9?
A waste of time 🙄.
Perhaps Leica will come out with a film camera with 1/8000 of a second some day.
I must say that I've never had problem with flare but in truth I always flag my lens with my hand if the sun is hitting the front element.
Gregory