I thought the R7 was the most minimal? R7 is just the strap (and fastener) with the curved shoulder pad. The RS5 has the pockets/etc all built into the strap, the MOD system looks like you can just add (or remove) what you want to have what you want available. There's also a strap to tighten the R7 so it doesn't move around much either. Anywho, just giving the info I've researched.
@etherial
How did/do you find the fasteners? I don't do tripod work at the moment, so being able to hot shoe won't be a problem.