I really like the speciality outdoor slings. I like them on rigs I might carry for some distance. last fall I had a mule deer hunt that my son was guiding me on, he is 22 and full of piss and vinegar. on opening morning he took us up the mountain in the darkness, its a good thing because I would not have hiked the vertical if I saw it in the daylight, LOL. I was carrying my blaser r8 with a TBAC ultra 5 on it.
The sling frankly saved me, I had my kuiu backpack on which doubles as a daypack, although kinda large for just that. and the last 1000 feet of vertical was boulder hoping large vehicle size boulders. That particular sling can be split and one strap put over your head on the other side of your neck. I was able to keep my balance, reach down, stoop, jump etc without fear of the rifle sliding off my shoulders. I am not the most nimble anymore and a broken leg in that situation is a 25k helicopter flight out. I was very very happy with having that sling on. In regular configuration the rubber is pretty grippy and takes quite a bit to slip off your shoulder.