I've made the statement in the past that the M Monochrom has the lowest non-uniformity of any sensor that I've used. The low-noise level is amazing. I've looked at the numbers using custom code, but never generated metrics on performance. That- I used to do for digital sensors in the early 1980s.
After several years, I can verify that comment.
This table is from the above website, the last two columns are dark signal non-uniformity (DSNU) and Photo Response Non Uniformity (PRNU) is - like Fixed Pattern Noise (FPN) - a way of expressing errors in the output from sensors. The lower the value, the better the raw image. I will never sell my M Monochrom, or M9. My M8 is one of the last in the production line. I'll keep it as well. 35 years ago- would have selected the M Monochrom based on the last two columns alone.