considering mounting an RMR on a handgun--wondering if anyone (1) has experience using them; and, (2) what dot do you prefer?

seems the choices run from 3.25 MOA to all the way up to 12.9MOA. Any input on size, color, and shape would be helpful.

I'm not wed to the RMR, but it seems to be the one that gets the best reviews (and co-witnesses on an M&P CORE)