I have a 5D2 (actually 2 of them, one is for infrared), and I think I actually prefer the ergonomics of the 5D2 to the M9 I'm renting. This isn't a rangefinder vs SLR view (I generally prefer the rangefinder), I just think that the Canon does a better job of presenting relevant info when shooting.
In terms of lenses, I've rented the Zeiss 35/2 and 35/1.4. The f/2 is a very good lens. The f/1.4 is extremely special, but is heavy and large (I remember it being comparable to the Canon 24-70 f/2.8 Mark I). The huge aperture is nice, but most of the time, the f/2 will be a better lens than most people actually need, while also being less expensive. I prefer the Zeiss 35 f/1.4 to the Canon one, but I remember the comparison being very close (a bit more IQ vs weather sealing and AF).
The 5D2 definitely looks more imposing though, especially with the battery grip. On vacation in London and Paris, other people stared at my 5D2 with 24-70 and gave me a wide berth or kept saying "wow, look at his camera" even if other people had a 5d3 or 5d2. However, no one (except me) acknowledged/bothered the M9, M8, and M6 users I saw. Heck, my friend and I were in a car dealership, he was using a 5D3 with the Zeiss Makro Planar 50 f/2 while I had the M9 with 75 Summilux (we were taking pictures of a Ferrari that was randomly in the dealership). Friend got offered a gig to shoot a concert, the guy didn't even look at me, even when I changed lenses like 3 times.
In any case, I think the ease of use of the M9 is over rated as I haven't found it to be as convenient as people claim (slow write speeds, slow menu, slow image preview, awful screen, not very helpful viewfinder info, terrible battery, meter is easily fooled). My Zeiss Ikon has been the best rangefinder I've ever used so far. If only Zeiss or Cosina would just sell a full frame digital version of that, I'd be extremely happy getting one.