RMR are bombproof. Has passed all .mil tests with flying colors. Hard to go wrong with RMR -- but depending how you train etc... that open emitter is going to get filled with dirt, water, etc... and you won't be able to see shit.... but the RMR is still one of the OGs of the RDS for pistol use next to aimpoint...

SRO is a consumer grade optic. Not saying it sucks - It doesn't but - just setting expectations. It is definitely not the hardened optic that the RMR is - the SRO is fragile in comparison -- It will break far sooner than a 509, p1 p2 or rmr... skip it if it were my money.

Just a thought --

Reality - the enclosed emitters like a 509 or aimpoint p1/p2... are the way RDS's are headed -- so with that said -

check out the holosun 509 or the EPS - if you are considering the SRO -

Aimpoint P1 and P2 are bombproof - have a long history with mil and le use - not the optics themselves - I am referring to
Aimpoint products -

The new steiner mps is pretty bad ass as well -- the company is 'okay'... but the optic is great.

also - check out sage dynamics yt vids - does some brutal reviews ... that can also maybe direct your decision process.