I own a couple black rapids and have tried several other strap brands. I can honestly say they all suck IMO. I got a SpiderPro Dual Camera System and it holds my canons like they are pistols on my side, a time tested way to haul gear w/o making your shoulders, chest and back sweat like mad on a hot day because you have straps on. I used to practically choke myself when i leaned forward at times, no more problems there anymore either.
If you want to check it out its here:
No i wasn't paid to tell you this, and no this wasn't a commercial.
The BR is the way to go with 2 bodies and 2 large whites.