On 12/05/2012 4:17 p.m., nospam wrote:
In , Mxsmanic
wrote:

Niche product, needs filters on the lens (instead of being able
to do that in post) which negates the high ISO partially or fully.

What filters are needed on the lens?

usual ones for b/w are red or yellow, but also polarizer and others.

Most of the time you'd need to use colour filters on B&W
(outdoors/daylight), you're probably not going to want or need to use
above base ISO, so that's probably not a significant disadvantage.
The Leica M9 sensor however was hardly state of the art for quantum
efficiency or read noise, so I wouldn't be surprised if the mono version
was not as good in any way (including resolution) as current FX canon
and nikon "colour" cameras at high ISO, simply converted to B&W, with
filter effects done in PP.