It's pretty much impossible to put the differences into words, in terms of simple resolution the results I get with my P65+ and a tripod mounted 120mm Macro are so far beyond what the M9 can deliver that there's simply no competition. However, versus Canon the results are far less clear cut. My current travel camera is a 5D MkII with the 24-105 IS. It delivers dependably great results out to the edges at f8 and f11, but corner quality is poor at any aperture, and at f4 or f5.6 I'm often a little disappointed right across the frame, consequently getting the results I want from the 24-105 requires taking liberties with the IS and using the ISO setting aggressively!
The M9 just provides more options at lower weight, but with the inconvenience of lens changes on the fly. Overall I prefer the look and feel of an M9 shot, it tends to have less of that "processed" digital feel (ie distant grass turning to uniformly coloured astro-turf!) or a slightly "smeared" look. Then there's the prime versus zoom question, as a huge generality (that's I'm sure more respected in the breach than the observance) zooms deliver outstanding definition in the central part of the frame, and perform well in both the near and far ranges. But the usual downside is poor performance out towards the edges and an intrusively "wirey" look to the out of focus areas. Hey, who's to say what's better, you pay's your money and you takes your choice!
i am not surprised that the 24-105 will give you smeared results....even the 24-70 has no real chance compared to pretty much any canon prime....and compared to leica primes....there is no contest....
i have been looking at m9 raw files and so far have not found the P21 look i was hoping for.....the files look a little sharper (as is to be expected) then canon files, but by far not the obvious difference between the m8 and the 5D.....high iso looks better then expected (for a ccd)....pretty good up to 1000, but no comparison to the canons or nikons....
i have not seen a good DR comparison, leica is saying that the high iso will be imrpoved with firmware and the conversion profiles are still not quite "there" (or so the leica fanatics say....)
i was really hoping for a m camera with a DMF look....but this does not seem to be it....and we will probably never see one....if i had the cash to just buy one for fun, i might, but 7000 is a lot.....
in a way this really showed me how amazing the 5dII is and how really amazing the files are that come out of it....and the 7d looks amazing as well....the combination of the 2 (with some other advancements i haven't even thought of yet) will be on the market in less then a year.....for about a 1/3 of the price of the m9....it is just hard to justify on any level....
i think the m9 looks like a great camera and i am sure it will make a lot of people very happy....and it really looks like leica did their homework this time.....
as much as i love RF....it is not worth that much to me.....
also: there are still SOME issues with IR (and UV as well?) and there are some corrections in software going on....some superwides still show cyan shifts and such.....much, much,much less then the m8....much improved....but still....
and then you just pick up the canon and shoot.....without any problems at all....