That's why for a self defense pistol it is important to have sights that clear the glass.

 

Was this the EPC something sight?  The one that looked like a small box of matches lengthwise on the slide?

Saw it in American Handgunner.  It had a tiny square window IIRC.

ETA: lol.  Should have scrolled down a bit before replying.

I've read of more than a few cops testifying to their RMR equipped handguns being good to go in other forums.

The RMR is rated to be waterproof to around 30ft if it is properly installed so that the bottom gasket seals against a true flat surface.  Most pistol slides are too narrow, and the gasket does not seal completely on the sides.  Trijicon sells a stainless steel seal plate you put between the sight and slide so it maintains a water tight seal.

Many dont even use the seal plate, and most everything I've read indicates the sight holding up just fine to exposure.  I carried my RMR'd Glock for more than 2 years before installing the plate and it has been 100% for that time.  I carry IWB so it is not often exposed to the elements (though I have shot in the rain and had rainwater soak through my shirt to the pistol without problems).  What it has been exposed to every day is a lot of sweat, that definitely finds its way between the slide and sight (I have seen traces when I've removed the sight for annual battery changes).  It has been 100%.

Water and sweat on the lens did not affect anything.  However, the dot is projected from the base towards the lens, so if big clumps of dirt find their way to the top of the sight, it *may* block the emmiter and you will lose the dot.  But anything that would do that would probably block the rear sight anyway.

Safariland IIRC makes level 2 and 3 duty holsters with a hood to protect slide mounted optics.

What he said.  At 46 the ability of my eyes to focus on the front sight is not what it was when I was in my 20's.  The RMR style optics on a pistol is starting look attractive to me.  It would also make the pistol sighting system more like my red dot AR carbine sighting system.

The new Leupold Delta Point Pro looks very interesting.

I work in a gun store. I've noticed a trend for older shooters to want these. Either by sending their slides out or picking up the S&W CORE. They are the guys who regularly go to the range and feel it makes them more accurate and shooting more enjoyable. I think this trend is here to stay, especially if the price on quality optics comes down some.

Gratuitous pics of my rig

I gave it a go with a full size red dot unit and that was bad enough.  Too hard to pick up the dot compared to a red dot rifle.  Regular sights are faster.  The red dot came off my pistol pretty quick.  Failed experiment.

I only noticed two times when my RMR glock 19 was faster than irons:  shooting moving targets (like steel on a wheel) and long distance shooting (25-50Y).  It wasn't harder to carry, but since my OTHER CCW guns only had irons, I didn't like switching from one method to the other all the time.

I had to sell the RMR and now the slide to fund two crowns (and a root canal), but I know I'll come back to a red dot someday.  I'm thinking next I'll build one around a G35 or G40 just as a HD gun.  I also may try out the Deltapoint Pro instead of the RMR, even though I liked the RM02 a lot (I tried almost ALL of the models).