>>4320140Man, I have tried the lot. Standard straps, Holdfast gear, chest harnesses, the works. All have some critical failure like the Holdfast is just too awkward to use with two cameras.
For full days shoots the daddy for me is the Spider Holster. Puts all the weight on the hips, not the back (big shout out to all the other oldfags), easy to move around and you can switch cameras in seconds. Great if you are shooting an event with a couple of different focal lengths.