Leica Quality

In my experience the quantum leap in digital dark room in terms of programs like photoshop and plug-ins from Nik or OnOne, Topaz, etc. you can create amazing Prints (up to 11"x14", I am not talking for web view only) with cameras like even old canon XT (7 mp) and 40D (10 mp); and also after scanning with a cheap canon film scanner of old 35mm. film negatives.

Unless you are a professional and photography is your source of income, expensive dslr and cameras from companies like Leica has basically little value added and in some way, waste of money. For most amatures what you need is a camera like canon 40D with good lenses and good digital darkroom experience. The proof is in viewing. If interested, check my link below:
http://www.flickr.com/photos/11466180@N08/?saved=1

I think you need to go to big enlargments of tripod mounted camera images to see differences. The Nikon D3x (8000$?) likely surpasses the M8 in image quality, and gives the M9 a run for its money, or vice versa. What has been found is that Leica lenses are better than current digital bodies. But it all depends on what you need. For truly fine large enlargments many still use the better MF cameras, either digital or film type. The better MF digitals are better than the best from Leica, Canon, Nikon, Sony, etc. The Canon and Nikon DSLRs probably beat Leica for jpeg quality, given the Japanese edge in image mathematical treatment and control (firmware), but Raw is the way to go for best image quality.

What do you really mean by mainstream Leicas or DSLRs? You are speaking apparently of high quality in the M9 league, so I imagine that you are referring to the highest price DSLRs? The M9 is not mainstream in price, nor is the D3X, whereas the Canon 5D Mark II or Nikon D700 are probably closer to that. Mahmood is probably right for those of us content to show images on low resolution monitors, or in prints of 8 x 10 inches or under 11 x 14 inches. In those cases, what need for a D3X or an M9?

In my opinion the M9 gives marked image quality improvements over the D700 for example. I think it's mostly down to the (lack of) AA filter though - basically never needs sharpening, and I prefer the colours out of Lightroom raw files.

The reason I have held off on an M9 (or similar) is that I am not sure it is a good investment (unlike my film Leicas). In terms of IQ I can make the following observations.
The difference between a great DSLR like the 5DII and an good APS-C body like the 7D is actually not that big until you print very large or use higher ISO. For example at 11x17 the 7D and 5DII images are hard to tell apart at low ISO. Bigger than this and you can start to see the differences but I suapect this is more due to the lenses than the bodys (I basically shoot L series zooms, primes and lenses like the 17 F4 TS and 85 F1.8). I suspect that the high pixel density of the 7D is pushing the lens performance too far and big prints show this limitation. Interestingly even at 11x17 my old (8.2 MP) 1DIIN puts in a very good performance.
In terms of film comparisons a 35mm film body is clearly worse than the 7D (never mind the 5DII). Even when carefully scanned - I use a Nikon 9000 and 5000. Moving to MF my Mamiya 645 (film) is on a par with the 5DII although I tend to slightly prefer the Mamiya images. Going bigger with my Fuji GX680 yields clearly better results than the 5DII but the negatives scan into very big files (500MB + in 16 bit TIFF) and the Fuji lenses for the GX bodies are amazingly good.
Returning to Leica I suspect that you see more differences due to the lens than the body / sensor. Indeed I suspect that the Leica sensor is probably inferior to the latest Canon and Sony designs (I believe Nikon uses Sony sensors). We are in the realms of digital signal processing and Canon uses a lot more processing power than Leica. Indeed it also manufactures very high specification sensors with state of the art micro lenses and noise handling. I suspect that the sensors in the D3X and 5DII are better than the Leica sensor - if they are not the next generation soon will be as these manufacturers are spending much more on research and development than Kodak was. Of course the Leica advantage is in their glass which is better.
I agree that not using an anti-aliasing filter may give Leica an edge but the D700 is an older 12MP sensor. Interestingly Canon appears to have maxed out in MP density as the new 1DX is only! 18MP. They seem to be pursuing a speed and high ISO performance avenue. While I am not a great believer in DXO mark their tests show the 5DII and d3X test higher than the M9 on any of their tested attributes - resolution not being one. Indeed Amateur photographer in the UK shows the d3X and 5DII out-resolve the M9 - even in Raw although the M9 puts in a very good performance.

This question drew my attention also. As an outsider looking in I had always supposed that image quality was not the only or even main reason for Leica being able to sell almost every M9 they can produce. I had imagined it had more to do with continuing the M rangefinder tradition. Continuing the same exposure control and focusing method so familiar to longtime Leica owners. I think that even if Leica had brought out a bang on hi spec digital rangefinder but it didn't handle as close as possible to a film M then it would have been a failure no matter it's image quality. For myself I would love to have a digital SLR that has manual focus and has the same exposure controls in the same place and has the same feel as my OM-1.

Yeah.....the chance that will happen is about the same chance as me flapping my arms and flying to the moon.

It isn't just the camera. Leica lenses are just superb. The build quality on Leica's is always first class. Engineering can sometimes go awry, but the quality is top notch.

I guess this has been mentioned before elsewhere, but another reason for choosing the M9 (or M8) is their very small footprint compared to the considerably larger Canon and Nikon full frame digital systems. Maybe an M10 will someday offer even better performance, but the fact that Leica is a comparatively small company and their sensor provider (Kodak) has sold that part of their business may make it more difficult for Leica to continue its digital camera development in the short term. On the other hand, an M10 may be far in the future, given the record digital camera sales of Leica this year and the demand for the M9.

Now I've always loved rangefinders and have owned many including a IIIf and an M6 but, give me a middle of the road digital camera with auto focus and a good zoom lens and any perceived superiority of Leica over everything else will disappear in a hurry. Those old tech cameras with their fixed focal length lenses and manual focus just can't keep up anymore.

Canon has nothing to worry about as far as market share goes, so they might as well make their newest & best full-frame sensor available to Leica. Different animal in comparison to manual focus rangefinder. No one who is willing to spend $8K on a M-9P is even considering the full-frame DSLR, so Canon would be wise to let Leica use it's best sensor. Otherwise they're missing out on a nice sale.

I haven't borrowed a M-9 yet to play with. I would love the chance, and it will happen sooner rather than later. I love the Leica glass with my results from my M-6TTL's. Color, sharpness, shadow detail, etc. I can drum scan a neg and make murals. So the sensor and it's firmware/processing are key.