At this point, I doubt a M8 would be the way to go. True, it'll give you the rangefinder experience, but IQ will be outclassed by 2011-2012 cameras. By IQ, I don't only mean sharpness (the M8 is good with that aspect), but also colour rendition, dynamic range and ISO performance.
APS-C cameras and even Micro 4/3 are really impressive, especially for the price. I use a Sony NEX-7, and I'm always astonished by the results. It has a very thin AA filter, and sharpening is incredible, so are colours and DR. It's also very lightweight, sturdy, has a side EVF (it did take me some time to adapt to it, but it's incredible, it doesn't have the "waterfall effect" on lesser EVFs.
Lumix GX1 and Olympus OM-D are also very impressive. I've seen incredible 16x20 prints from all these cameras. Same goes for the Fuji X-Pro 1, even if I really don't like the "rangefinder wannabe" style of the camera (an MP or M9 is a rangefinder, not this), I prefer Sony's modern approach.
Another factor is the cost. A brand new Sony NEX-7 is less than $1200, an OM-D is $999... Even if you add $200 for a good adapter for M glass, we're still far from Leica's range, even used!
For all these reason, I strongly suggest NEX, Fuji or M 4/3 in our day and age, except if you can afford the M9 without selling a leg and absolutely want the rangefinder experience. But believe me, the NEX-7 isn't that far from it. Once set up, it's so instinctive to operate, nothing like my old SLRs. But it is a different approach and philosophy, and I understand people can disagree with it.