I sold off my Leica M4-2 a couple of years ago to invest in a digital system for work. I had always regretted doing so, until I picked up my Mamiya 7. It is such a joy to use, is simple, fast, and the picture quality crushes my M4-2 with a summicron 50mm f/2.
The only thing I don't get anymore is the occasional jealous looks from folks when I had my Leica- the Mamiya doesn't get those same stares, which is probably a good thing.
Don't get me wrong- the Leica was and is a great camera. but for less than the price of a Leica lens, you can pick up a whole Mamiya system that outshoots it.
I do miss shooting with the Leica, as it has a great feel, but I am super content with the Mamiya decision, and don't miss anything else about it.