I've had an Optech Pro strap, Blackrapid RS4, Sun Sniper Steel strap and am now on a Sun Sniper Dual Harness.
The Optech was good until I got a 100-400 for my gripped 50D when I found the weight made my neck sore. I sold that and got the RS4, that worked fine. When I got the 1D I got the Sun Sniper steel as a stopgap until the dual harness came in.
I would have stuck with the RS4 and Sun Sniper Steel if I hadn't wanted to carry two bodies at once.
I looked at cheaper copies but with several thousand pounds worth of camera hanging from them I didn't want to risk it.