I started with some leica glass temporarily on a m4/3, then finally got a M9, recently sold my M9 to replace it with a nex7 (and will add a ricoh + M module as soon as they have a built-in finder, or a leica evil if they make a good one).
The problems with the nex7 and wide lenses are not worse than the problems (colorshift) in the M9 with the same lenses!
With the M9 you never can frame exactly, so you loose some 10 or 20 % off the image anyway.
The lightmetering in the M9 is barely usable.
The color output is variable, from very nice to largely questionnable. Nice skintones and ugly reds, and rarely exact or realistic without cautionous PP.
Moiré can show up in landscapes (...!) if you process your raws with LR (which comes with your M9)
Dust is a problem, where my nex7 simply shakes it off.
The final picture quality can be marvelous, better than what i have seen in other 35 mm cameras, but rarely without lots of post processing and often you would need two shots to be sure to have the metering right.
With a Digilux 2 you miss the resolution, you miss the dynamic range (but you won't need as much , as it is very reliable in metering the light...)
The Digilux 2 nearly never misses a shot, and has marvelous colors not needing any post-processing.
I predict that eighter leica will show up with a nex7-look-alike camera with the Ricoh-M-module sensor (sony), or otherwise they will end making lenses only, and Ricoh will make the best bodies in future...
So i understand the ones that use Leica glass on non-leica cameras.
What i do not
understand, is those who buy a M9 and put a non-leica lens on it...
worst of both worlds....
Even the swiss leica dealer who sold me the nex7, asked me: "you sold the M9, but you kept the glass i hope? You made the right decision"...
I simply do not like the M8/9 ergonomics. The range finder is great, that's about it.
Whenever I see a used M9 at a reasonable price, I think about it. I could afford it if I wanted it, but spending just a bit less than €4k on a camera where I know that it's shortcomings drive me crazy seems wrong to me.
I do not care much about crop. A 25/2 would be nice, but I can live nicely with what I have, APS or not.