how do they work differently and what is the best oen to get? I saw a few at a camera shop recently but did not get a chance to look at them too much. I knwo they have a stabalizer in them and somehow store the image differently.

Basically, I'm working on the assumption of good f stop and a smooth head for you tripod. I shoot a lot of watersports action photography, so I have the super tele's from Canon. When I shoot the 400 f2.8 or the 600 f4 IS, The head I have for my tripod is actually a floow spotlight head for the theater. A lot of shooters use a fluid head, like video or film shooters. Too slow for me. Like the speed of the follow spot head, only thing is, it doesn't lock in place. It wants to balance back to a zero point.