SpeedTek sayeth:
none unless you gotta carry it. then 2 pt sling
In sooth. That's why Pele invented quick-detachable swivels (Attachment 1.) See, when venturing afield, you hook up the sling. When used around the house, you don't. The weird funky-looking piece of metal is what I threw together from scraps just to temporarily try out the concept of a slung shotgun... forty years ago. Worked well, so I never bothered to "improve" upon it.
The whole rig with an extra barrel is Attachment 2, my full-choke 30" waterfowling barrrel, and (mounted on the gun), my upland / defense barrel with a Polychoke. One of these days I plan on getting a slug-rifled barrel with sights. Then I'd really be tacticool. Slug shells shown.
Oh, the "miles" and "gallons" this old Mossberg has seen. I named it "Irving."
Frankly, this old-timer got so used to handling a two-point sling for so many decades, that I don't think I can handle anything else. Old dog, old tricks. So I can't
recommend anything else. So go with the majority.
Terry, 230RN