I use one. Pete Weber Uses one. Thats good enough for me... hehe Advertisment at its very best...
When i started bowling, i needed help to get good revs on the ball as young boy, wasnt the strongest kid on the block. Ever since ive used one, slowly upgrading from ones the simply help, to the one you describe where it can do nearly anything for your wrist. The only reason i still use it is because, it just feels wierd without it. Bowling is a game of Feel, and some people have a Feel with a wristguard, like me, then let them use it. It might restrict my revs, but i dont mind, i can still throw a good shot.
However, I do take mine off for spares... just a small habit of mine to allow for total breaking of the wrist and no revs on the spare ball. anyone else do this??
Later Da Cowman!