Reading this thread everyone's experiences are different and that's what will form their opinion. I like to use both rangefinder and SLRs, but in my experience Nikon SLRs are very reliable whereas the legendary reliability and sturdiness of Leicas have been overstated.

I have an M3 and used it for years, then dropped a camera bag with it inside from about 1m. Mirror separated and viewfinder went black. I was then going to use it for wide-angles with an auxilliary viewfinder, but the shutter then jammed.
I have had an M2 shutter jam. Luckily disassembling the shutter release collar seemed to fix the problem and everything now works fine.
I have a Leicaflex Standard that had a shutter break (I think a string broke holding the shutter curtain).

3 x Nikon F4, Nikon F3, F90X and FM2n - no problems whatsover (and I am much less gentle with the Nikons).