I have several of Larry Vickers' slings, and they are absolutely top notch. I deployed with the original version last year, though I didn't use it exclusively, I did use it almost every day. For someone who wasn't out patrolling, but still had to lug the boomstick around with and without body armor, it's a great choice. My only gripe was that, with a lot of 'furniture' attached, the sling was a little bit too narrow to be really comfortable without armor. They must have read my mind, though, because there's now a wider, padded version out, and it's freaking awesome. I have one for my own AR and one for my M4 at work.
If you buy one, though, I would go for the original style adjuster, which is machined from aluminum, vice the cheaper injection molded one. The difference is made pretty clear on BlueForceGear's site.
The only other sling I used was a 1-point with a QD for convoy ops. It was a little easier to manage if I had to get out of the truck in a hurry.