I've had a Sig Romeo5 on a 5.56 carbine and a 20g shotgun without issues, however, the AR and shotgun that I keep "in service" at my house wear Aimpoints...an H1 and a T1. It is hard to beat the Aimpoint battery life since I keep those on constantly!
I run Romeo 5s on both of my steel challenge optic guns. Great optic for the price. The motion activated dot allows me to leave it on always & aside from losing one of the adjustment caps, I’ve had nary a hiccup with either. (FYI: Sig replaced the lost cap for free with no more than an emailed request)
MSR is a budget sight and not as nice as the Romeo 5 IMO. I base that opinion on handling, mounting and boresighting the optics. Otherwise both are fine, both are made in China and both seem to be equivalent in quality to Holosun, Vortex, Riton, etc. that sell at similar price points. Optics are a competitive business and you tend to get what you pay for in most cases. That comment should not be interpreted as negative. We live in the golden age of <$250 red dots that will serve their function quite well.