Both that Black Rapid RS-5 and the SunSniper Steel sling strap look pretty neat. Does the body flop around too much if you're on the move? Unfortunately, all of my bodies have Stroboframe quick-release plates mounted onto their tripod receivers so retainer systems that use up a tripod socket won't really work for me since it would be in the way of being able to set the plate into its receiver. I do like the sling-style strap idea however, and I may just get one anyway.
That Op-Tech strap also looks interesting, but I think those bodies would flap around too much with that. I bought a "Cablela's Pro Binocular Harness" ($19.99) which I'm very happy with. Although, it's probably only good for lighter bodies and shorter lenses, but it's darned convenient--and the camera doesn't flop around at all, yet it's ready to shoot instantly. I loop the Nikon strap over my neck as well for extra security.
Between the Cablela's harness and a couple of ThinkTank lens bags on my belt, I'm good to go, although I may give that RS-5 sling strap a try. When I get a second body, I was planning to pop for one of those $600 leather gun-style holsters. Very pricey, but I think it's worth it for the ultimate in quick access and secure stowage. I've also looked at those other "hook and retainer" belt systems, but they just leave the gear too prone to bashing into things.