Points well made. Like the OP, I began shooting with a 35mm SLR (a Nikon F2AS), later progressing "through the ranks," acquiring a couple of Hasselblads (a pair of 500c/ms and a 553el/x) as well as, about 12 years ago, a 4x5 Linhof. Along the way (about five years ago), I picked up, on a whim, an M6 with a 50mm Summicron, thinking that the camera would serve as little more than an adjunct to my 35mm shooting. It took a good year or so to feel comfortable shooting with the camera - curiously for the very advantages you named above. Once I became familiar with the camera, however, and came to realize its many virtues (unobtrusive, quiet, quick focusing, low light accuracy, etc), I began using the camera for a greater portion of my 35mm shooting. In fact, I have come to love shooting with the camera so much that I have added an additional body and five additional lenses - in effect building a separate system that I use almost exclusively for my street shooting and documentary work.
Originally Posted by cliveh
What is important to point out, I think, OP, as others have suggested, is that the rangefinder is a different beast intended for different purposes. Your dilemma should not be framed as an either/or proposition. Keep the F6 and build a second system. For macro work, for shooting with super-wide angles and for shooting with telephotos, the SLR excels. But for candid shooting, street and documentary work - for pretty much anything in the moderate wide angle to short telephoto range (I refuse to use the auxiliary viewfinders) - Leica rangefinders are primus inter pares. Yes, they are expensive; no argument there. But amortized over a lifetime their cost is quite reasonable.