The RMR is a great sight and tough as nails. I also found the Burris Fastfire III to be a wonderful pistol sight that replaces the rear iron sight. Both can be used to rack the slide, with either a hand or a solid object such as a table or door frame. The RMR is a bit clearer and brighter in my experience, but not by much. That might differ from person to person.
“Malo periculosam, libertatem quam quietam servitutem." (I prefer the tumult of liberty to the quiet of servitude.). Thomas Jefferson
"All that is necessary for the triumph of evil is that good men do nothing."
-Edmund Burke, Loosely translated from Thoughts on the Cause of Present Discontents. (1770)