Optima 2000
I have Optima 2000 sights on several pistols. As my aging eyes are no longer able to focus clearly on front sights the Optima has ben a godsend . I find the sights easy to use and very reliable. Have never had a problem with the zero shifting and they have improved my shooting ability with pistols.
I find they are far more desirable than the bulkier tube type red dot sights and the dot is much easier for me to pick up. If you need a red dot and can live with the stupid cover they provide they are the way to go. If I could find a way to use them without the cover having to be on to turn them off they would be perfect for a carry gun, (Not that I can carry here in NY).
Their small size is a plus, and they are rugged. I just purchased number 3 and am debating which gun to put it on.
No experience with one on a shotgun, but they should work OK, although zeroing may be a chore.
My $.02