Curious if the OP has made a choice. If not, I'll add that soon after I bought my R4M I developed doubts about my ability to focus at 50mm. However, I've found it's do-able. Not pleasurable, but do-able. The fit and finish of the camera are fine, and I find it easier to hold and carry than a Leica. To the best of my knowledge, no one has ever heard the shutter outdoors. Indoors, with echoing off walls, etc., it's a different story, even with a Leica.
I've acquired an M2 to complement the R4M. The plan is to use the M2 at 35, 50 and 90, and the R4M at 21, 28 and 35, depending on circumstances and my whims.