I'm a little surprised you'd do it on our rocket ship multi-hull, Larry. Having said that, I know you wouldn't do that if it didn't work for you -- and you'd certainly not advise people that it can work unless you felt so.
In the for what it's worth area, I'm a bit more conservative and just don't think a line clutch or stopper is really the way to go for a sheet.
I just haven't found rope clutches to be too reliable at not hanging up when you're really trying to let the line go. They certainly aren't as fast as unloading a winch. Aside from the friction, there's that tendancy to have a line "hockle" or twist hang-up which happens to us when released.
By the way -- are you going to the Annapolis for the boatshow, Larry?