If you have never used one, it's difficult to explain the advantages without photos (note to self: another photo project!)
The Ching Sling allows you to sling the rifle in a way that is comfortable to carry, yet immediately available. It includes a loop that permits your off-side arm to put tension on sling for more accurate shooting.
I favor it because when worn and used properly, your rifle can be slung alongside the body and brought up for immediate use without "unslinging" the rifle. It can also be moved from the side-slung position to a horizontal position across the chest - and remain that way without the use of the hands.
It's quite effective and well worth the investment.