Stephen, the handle makes it a completely different workout. I wish I could demonstrate, but I wouldn't discrace a camera with the 2 crappy balls I have. Basically, you use the grip one to strengthen and rehabilitate more specifically for golfers and racquet sports, while the ball is used for general rehab (this is according to the packaging and their own research.) While you do the rotational spinning of the standard powerball, the grip ball is spun with a motion similar to turning the throttle on a motorcycle, thought it too can be spun with the rotational method. The best benefit I've found is the ability to switch the grip... you can "choke down" on the stick to get a more "round" workout, choke up to get a more "throttle" workout, or flip the stick around so the ball is at the bottom of your hand instead of at the top. All in all, it's completely different than an "in the hand" powerball.
Also, I've seen a gyro at the Milwaukee Public Museum that is actually a 20" bicycle tire with handles on the axle. I have seen similar smaller (8" tire) gyroscopes used in Physical Therapy that I would have to say go much faster than even a powerball (if you could measure the speed) but don't provide as much of a workout because they are used with both hands and don't have the versatility of being able to be carried in your pocket.
On a side note, I think a larger version of the original Powerball with built-in ear-type (not handlebar-type) handles would provide an awesome upper body workout for both arms at the same time.
Last edited by dragonriot; 15-03-2006 at 20:10.