One of the neat things about using a Leica is that you become part of an "elite and opinionated crowd". That comes with the anachronism of using a camera that hasn't changed much since the first M-series was made in the 1950's.
My opinion: the viewfinder ain't no problem. I've had the over-40 eyesight condition since I was 34 and I wear progressive lenses. I can use the framelines fine in the .72 viewfinder. At one time, I used a 28mm with an M4-P, and didn't have any difficulties with the 28mm framelines. I couldn't always see the entire frame in the viewfinder but I knew where it was and what I would get on the film. The viewfinder flare condition has happened a total of one time to me.
I consider the Leica a superb camera for quick shooting of candid subjects. Because of this, precise framing is not a priority and zone focusing is quicker than using the rangefinder. An SLR is more precise.
When you get one, we'll teach you the secret handshake.