A few weeks ago, I saw someone using a sling-type strap that looked very comfortable. I was unable to catch up with this shooter to get more information, but I liked what I saw.
It was a two camera rig, with a sling on right and left side. There was a crossover (X) on the back, and maybe a second adjustment buckle across the back below the X. At the arms, the each side wrapped around the shoulder and under the arm. There was no strap across the chest area or any other front-side connection that I could see. Strap appear (at a distance) to be approximately 1" wide leather harness with some adjustment buckles.
