you might check out peak design. I have one of their beta models - uses an arca plate, slides into a gizmo that goes on your belt, bag strap, etc.. I used it on a small bag strap to carry the camera, and put the 70-200 etc in the small bag. Not quite drop and baby grab fast if it is on your belt. I tried the spider but oof the ball nub was a PITA - I think they updated the design since then.

Peak also has a strap that is easy on/off. I have a BR and use the arca clamp for all my strap needs currenlty