Well, who knows what I'd do in a real HD situation, but I'm pretty sure I wouldn't be messing around with my red dot sight on/off/size knob unless it turned into some long stand off deal.
Serious SG's should be set up for your own particular needs and situation... is my opinion. Here's what I've done about a red dot for MY situation.
I opted to add a red dot sight to my HD shotgun only because it is also my CD (longer range) shotgun. Yes, I've read ALL of the threads on TFL and THR about keeping a HD SG in high speed, low drag mode. I only have one gun, etc.
To preserve all of my options, I installed a see-under saddle mount for the red dot. So, I can still quickly use my front bead or front of barrel or "aim by fit" or even "aim by gun-mounted light" when in my condo in a short range HD emergency... but if I have to go outside and shoot long range, I have some red dot help for my old weary eyes. I can hit a target COM with slugs at over 110 yards with just my front bead, but wow, it takes longer to line up as each month goes by. Bought some help.
My particular "under the bed" shotgun stash in a child-free condo allows the red dot hardware to be a "drag free" add on that doesn't interfere with fast front bead usage.
Your situation is what counts.
