Upload & Sell: Off
When I'm doing a two-camera hiking day it's a 7D with either the 300-800mm or 120-300mm mounted on the Velbon 730 with a Manfrotto gimbal head on my shoulder and the 5D2 and Sigma 24-70mm in my older Lowepro Slingshot 200 AW (carrying extra batteries, cards, lens cloth, blower, etc.)...and off I go.
As for a non-Canon strap, my choice has been the cushy soft, breathable, quick-release, Lowepro Voyager-C.
Hope this helps!