i think the canterbury ones are good. tacky and sticky grip makes a hell of friction, good grip. too bad they're expensive over here, so i just bought the gilbert ones
Matt Dawson wasn't a bullsh*tter and he wore them, so I guess for scrummies, and other players who need to master quick pick-up passes, they must be useful. As a flanker myself, I've never warn them in a match.
I think what some people miss is that additional grip, obviosuly it's only a slight difference, but can help, can help you maybe get hold of the ball even if you don't get a full hand to it. Whether it's a lineout, cheating in the ruck or any other time, but it's just not for some people.