Thanks everyone. It's really helpful putting tripod ball-head or pan-and-tilt in context with camera and user. Am I correct in thinking that 35mm and medium format users with ballheads use these for flexibilty during composition, rather than geared or slower movements?
One thing I've noticed is that the Bogen don't exist in England - I think it is marketed as Manfrotto in England. I can't find any store that deals with the JR tripod head system although having browsed through a warehouse internet store, the Kirk system seems to be highly lauded. The Arca Swiss - this must be in a class of its own. It's a ballhead to make every viking envious, but it's way out of my league ;-)
One of my worse fears about ballheads is loosening the slack, and then finding the whole camera set up crashes down at 90 degrees, risking damage to something, or snipping off a finger or two. Does this happen to anyone with larger medium format or large format cameras?
I do like oversized levers which scream out: "hello - I'm a lever - turn me". I used a cheap ballhead briefly and found that I had to use my nose to support the camera. Once with a 35mm camera, it poked out a contact lens because of its sudden movement when the tension was released - that wasn't too bad. But the same experience with a large format .....?!!