Well I've been using Leica's for many decades and happen to like the rangefinder, and I already had a bunch of M lenses otherwise I would never have bought into the system at this point given the cost, especially lenses.
My first M-mount digital was an Epson R-D1, which I got for $1300 as a factory refurb. I didn't care for the fact it did not have the full range of frame lines and required them to be manually switched, and the rangefinder was apt to go out of calibration without provocation. So I was delighted to sell it (for what I paid for it) and move on to the M8 despite the IR filters. And even more delighted to move on to the M9 because it didn't need them. And though I only moved on to the M240 because a great deal on a demo came my way, I'm glad I'm rid of the M9 given the whole sensor cracking/spotting issue, even if Leica does eventually find a permanent solution.
The one thing that has changed for me with digital is I no longer own two bodies as I always did in my film shooting days. The film bodies were smaller, lighter, much cheaper, and bought used could be sold several years later at no significant loss. And I could justify it because I would shoot different ISO, or slide film in one and print film in the other. Since digital I only need a second body in case the main one breaks down (which knock on wood has not happened to me with any M digital so far). I agree with Jaap the Nex (mine's a 6) is not an equal substitute for the M but the IQ is not bad at all, it was cheap ($450 brand new), it's small and light enough to be unobtrusive in my luggage (and does not need a separate charger), has a built-in flash, and it works well with all my M lenses. The worst about it to me is it's an EVF not a rangefinder.