I carry a BR system that has been retrofitted to hang the camera from the lugs like the OpTech system. I also use an underarm strap to keep the shoulder strap from slipping. Doing so gives me one big advantage. I lock the rear keeper near the small of my back. When climbing (e.g., onto a train car from below the boarding ramp), I can swing the camera back and use the front keeper to lock the camera behind me. Because of the underarm strap, the entire assembly is prevented from sliding back; the camera stays where I put it.

I am also experimenting with a system that holds the camera like a regular neck strap, but is longer and carried cross-body. This system (still in development) will allow the camera strap to slide, but through the slots on a much longer, but lighter non-slip pad. The latching mechanism would be a single latch for positioning attached to the pad. I am trying to use some old hot moldable plastic (such as is used in modern day casts and braces) as a stiffener for the pad; the material is light, perforated for air flow and will bend rather than break. It is also strong and difficult to cut when set, providing security. Part of the harness is an optional tether kit which, for those who feel the need, can use the tripod socket as a single or double safety option. If I wasn't using so many parts from other systems, this would probably be a good Kickstarter program.

I bought the OpTech sling as well. I carried my camera for awhile the way they recommend and I found myself with my hand on my lens all the time trying to make sure I wasn't going to run it into anything. Then I did like bsprague said and I reversed the male/female order, since I don't keep a grip on my camera at the moment where they suggest the other one goes, and now it hangs straight down. I don't have great big lenses on my camera, but I've never felt like I needed a reinforcement on the clips. I really like how secure my camera feels on both of the clips and it doesn't seem like it's straining them anywhere close enough that they might pop apart and drop my camera.

http://optechusa.com/utility-strap-sling.html

Ok, there's the link to the site where it has pics and a video of how the strap works. The male end uni loop is supposed to connect to the right side camera strap lug. I have uploaded one of the pics they have here and if you want to see more you can click the link for the site. They also include a female uni loop when you get the strap so that you can use it with a pro battery pack or other gear. What I did since I didn't like my lens sticking out and always keeping my hand on it was to take that male uni loop and move it to the left side of my camera and then placed the female one on the right and I connect both of them to the strap at once and then the lens hangs towards the ground.

http://optechusa.com/utility-strap-sling.html

Ok, there's the link to the site where it has pics and a video of how the strap works. The male end uni loop is supposed to connect to the right side camera strap lug. I have uploaded one of the pics they have here and if you want to see more you can click the link for the site. They also include a female uni loop when you get the strap so that you can use it with a pro battery pack or other gear. What I did since I didn't like my lens sticking out and always keeping my hand on it was to take that male uni loop and move it to the left side of my camera and then placed the female one on the right and I connect both of them to the strap at once and then the lens hangs towards the ground.