I own Benelli M4’s & M2’s, wearing Scalarworks mounts. Switchedem’ all from RMR’s over to newer SRO’s & never looked back! Personal choice of course, but some users claim the SRO “looks odd” and is not as indestructible/duty proven vs. the RMR..naaa..I have validated with lengthy runs, drops, & various abuse that the SRO is well built & plenty tough. The SRO has identical footprint as RMR, but SRO sits a tad taller (slight raise under frontside of optic) & a tad wider. For practical application on a shotty, the SRO has a rounder & slightly larger FOV vs. the RMR, which for me expedites & enhances overall sight acquisition. Further practical application, with the SRO u can change the battery topside/don’t have to dismount unit like with RMR’s. Don’t listen to haters who offer that the SRO can’t survive an IED attack or that it was made for pistols. Contact Trijicon & inquire about SRO applications or on Trijicon’s web site validating the SRO for shotgun use all day long. I have the larger 5 MOA dot size, just works for my eyes on shotties..also available in 2.5 or 1 MOA dot. I put my RMR’s on pistols being more compact..go figure!