I get enough questions about this that I've got a CROM and a Primary Arms red dot coming to test on my own gun.
My gun usually ends up being a loaner in practically every class. It's going to see at least a thousand shells in 2019 just in classes, all of them being heavier loads like buckshot and slugs.
Shotguns beat the shit out of everything attached to them. If it can survive a year with me it'll be a pretty good indication that the optic is a pretty good value option.
I should note that a couple of folks who have been through my classes have put PA dots on their guns with a CROM and have reported ~ 1,000 shells through the setup so far with no problems...so I'm optimistic.