While I don't have any of the RMR's, I did end up with a couple of the Trijicon, MRO's.
They are kind of a mixed bag. While the dot is fairly round, the glass is very clear, It doesn't seem to be in focus, at any distance, using "one" eye. Very odd for a "dot" sight. If you look through it while closing one eye, bad focus. But if you look through it with both eyes open (like you should!), then your brain does a good job of providing a pretty clear focus.
I just bought a Holosun HE530G. VERY clear glass, round dot, and NO focus issues, one eye or two. AND it's made of Titanium, so it ain't gonna break !
Mike