Well from my experience with the 28 1.9 ASPH is equally good on the Leica M8/M9 as it is on film Leicas M6/M7/MP.
I know some "experts" 🙄, on line like to mention all the negative things about the 28 1.9 ASPH.
Like it's to big and it's ...OO what ever.. And everyone is entitled to their opinion. Just as I am entitled to ignore them and just use and enjoy the 28 1.9 ASPH 😛.
In truth I love reading any and all information about lenes. To me, it's interesting to what others think, or more precisely how they think. How they test glass. What they feel is important in a lens. To me, that kind of information, it's just interesting.
However there is nothing, I repeat nothing, that even comes close to using a lens for a period of time, under all kinds of lighting conditions, and weather conditions at all kinds of apertures, on both film and digital like I have with "my" copy of the 28 1.9 ASPH. And from my first hand experience, I can tell you that the 28 1.9 ASPH is "all that" and more.
With its speed and sharpness and feel, it's an exciting lens to use.
I often use the 28 1.9 ASPH on my Leica M film/digital along side of my Nikkor 28 1.4 AF-D ASPH on my Nikon D3/F3T and it more than holds its own to what I believe is one of the greatest lenses ever made.