Trader Bill Keith has a great line of truely useful things for your African safari developed after many months spent in the bush. I have used his very high quality webb sling with the leather ends and recomend it highly. Soft and wide enough to be comfortable, it will not get sweaty even after a 12 mile trek. I do find, however, that a QD sling is very important as you get rid of it as soon as the final stalk begins. the last thing you need is for your sling to be catching in whatever it will when it is very important to be SILENT. The thong, although silent when the sling is in place, is far from QD. Hook fasteners are about as fast and simple as you can get. I don't worry about a few minor marks on the barrels of a hunting rifle, the sweat and blood from the trek and thorn scratches running into the action are of more concern.
All the best, Mal