JC, That's a cool head but I have some reservations about this and the pistol grip heads. I have one of the vertical ones and there is a tensioning dial on it (I use it on my Monopod). I've heard that with regular use they will slowly loose the ability to grip the internal ball. A true Ball head is the stronger choice IMO. I have a Manfrooto ball head on one tripod and just got a Benro copy of the Arca for my heavier tripod (used mostly for studio stuff or the Bigma).
The Benro head is like this:
Benro KS-2 Ball Head ballhead for Tripod+2yrswty - (eBay.ca item 290212141859 end time 04-Apr-08 23:15:24 EDT)
It uses a QR-2 quick release plate that you can get extras of for around $22.00 which is great if you have more than one body or lenses with tripod collars.
This is a very solid head that locks in all directions without much issue, Fast and easy to use. It has a panning motion as well that can be locked. So fine for Pana shooting as well. Ball heads are nice because they are more compact with very little sticking out to get in your way .
I've tried the Arca version (which is almost 3 x the $$) and no question it's a smoother head but I don't feel it's worth 3 x for that.
One last thing I like about a ball head is the ability to undo the locks and allow the camera/lens to "free float" . I've used it this way many times. So say I'm shooting a faster moving subject (cars, race horses etc) and want to have the support of the tripod and some stability. Just loosen the head and you can use it as a support but be able to follow the action in all directions with both hands on the camera/lens. So you're basically using it like a gimbal. The grip heads don't offer that. You must have one hand on the grip and squeeze the lever to move the camera.
The plus of the Grip head, is the speed to compose a shot. Simply grab the handle and squeeze as you move the camera into position.