I did not find this answer via search or thread-slogging so here goes:
I am very happy with my SMC ring buckle/webbing support system, but of course I can't leave it alone.
Right now I have webbing that measures out at 1 1/4" wide. It works really well in the ring buckles (it is cannibalized tiedown strap material).
What is the widest webbing anyone has successfully used in a SMC descending ring buckle?
(like this set up but w/ a prusik instead of a larkshead)