Yep, I mounted a Holosun red dot on my defense shotgun. I have been exploring #4 vs 00 and am starting to lean that way for the very reasons you outlined. The red dot lets me get back on target very rapidly. And co-witness is easy. I am not the world’s greatest defensive shotgunner by any stretch. I have a buddy who is quite handy at it who is teaching me. It is hard to break years of shotgun trap and skeet discipline. I think he wants to beat me over the head with my shotgun on occasion.