When it comes to shotguns, I often need a sling for short periods of time when duck or turkey hunting. The narrowness would not bother me at all on a 6-7 lb gun for that purpose. I use a couple of the double slip loop slings but then I have to stuff them somewhere when I've gotten to where I'm going and not forget them. They do make VERY handy turkey carriers however, if not being used on the gun. anyway, I like the idea of retractable sling in theory. But practice could be different.
My Darne is my first shotgun with sling loops of any kind. We shall see if I put them to use.