I've used both M series and a 111f. The M series is certainly more convenient to load and shoot. A 111f or 111c in good condition with a collapsible lens like the Elmar or perhaps Summicron is a good choice where compactness is most important. One must either trim the film leader or insert a business card in the film slot and load the film behind the card. I found the other differences between the new and older Leicas to be minor obstacles.