I have a Tiger Valley bag on one of my rifles. It is well made and works. Definatley handy having it on the sling. I like it best for short to medium range shooting. For shooting at longer distances I like a wider, softer bag that kind of wraps around the stock a bit, feels a little more stable. But for moving around, running a course, hunting etc... it is unbeatable. It keeps something else out of your hand and doesn't hang or swing like running a sling through the straps on other bags. Also doesn't interfere with the sling either using it for support or carrying the rifle.
The guy that designed it and the guy that make them are both here on the Hide, good people.