The quantitative data Dante Stella presented here:
The Leica Monochrom typ 246 and filters shows the difference in colour response between the MM and 246 is tiny, and that the MM and 246 both have major problems with red filtration.
This is why Leica only makes yellow, orange and green filters for the Monochroms.
If you have an MM that works well, I’d keep it and put cash aside for the M10M in a couple of years. The 246 disappointed me, particularly in that the live view was hopeless, and that the better high ISO performance did not maintain the image tonality like the MM did.
Marty