Re: URGENT - Quick Decision Needed......
Points in favour of the M would be that (i) it will still work if you run out of battery power
(ii) If the camera developed a fault you could probably get the M fixed whereas at this point in time the R3 might be a problem due to lack of spare parts (especially anything electronic). Some dealers I understand won't take that model because of that reason; it makes it difficult to give a firm guarantee. Your post in the R3 thread makes it clear you're very fond of the camera though.
(iii) You've already mentioned the size advantage; more so with the lenses. I'm not sure I'd want to cart two wides so close in focal length around (and might even lose the 50mm if I wanted to travel really light).
If I had all the money I've spent on drink, I'd spend it on drink