My 2 cents? If you’re deciding between the RMR and SRO, get the SRO. 5 MOA being my preference. Both are great optics. I’ve run an RMR on a G21 for about 6 years. No complaints with the RMR, other than what is, to me, a small(ish) window size. I put an SRO on my G34 MOS competition gun. Amazingly easy to pick up the dot with the larger, clearer glass. Granted, I only have about 5K rounds thru the SRO so far, but I like it enough that I bought another one and slapped it on a G45 as my daily CCW. Both have performed without issues.
I understand that it might not be quite as robust as an RMR under extremely harsh use, or torture tests. And it’s always good to plan for worst case scenarios. However, since I have no plans to deploy to the far reaches of Asskrackistan, if I SOMEHOW manage to damage it, I can most likely survive using my iron sights until I return home from the supermarket or hiking with my dogs. Let’s be realistic. With any of these quality optics, if it’s going to go tits up, it’s most likely going to be during the many rounds you fire in training and practice, rather than during the remarkably slim chance that you need to fire X number of rounds in defense of yourself or others during the course of your daily life.
If I was still working the mean streets as a police officer (25 years, retired for 10 now), I wouldn’t hesitate to use it, or an RMR. The ease of getting faster, more precise hits far outweighs any potential downside. (For me.)
With ALL of that being said, decide for yourself, and use whatever gives you that warm and fuzzy feeling. If not having the absolutely most rugged sight is going to cause you to wake up in a cold sweat in the middle of the night, get the RMR. Ultimately, it’s your a$$ and your peace of mind.
I’ve used both L&M and Jagerwerks. Both did great work. Jagerwerks did my last one, my G45. Very fast turnaround time and a very precise cut. The SRO “popped” into the cut, with no perceived play. I had them leave the slide cut uncoated, and just taped off that area and sprayed it with some black Rustoleum high temp paint. I’ve done that on my last three slide cuts, and it’s kept them rust free. But I live in low humidity Nevada, and haven’t needed to wade thru any swamps lately. YMMV.