Hi All,
In the end I bought the O'Connor 1030D. "When you buy decent gear you only cry once", as someone suggested.
Wish I'd bought one years ago now. It is on a completely different level from the Libec/Manfrotto stuff I've owned for video before, and substantially better than the hired stuff I'd played with, too.
Despite being only slightly heavier than the Libec I was using, it has lovely damped motion, adjustable counterbalance that really works for light loads as well as heavy, and hold the head steady as a rock at ninety degree tilt. The adjustable friction just works.
I'm sure an Arri geared head is even better, but for now... the O'Connor is just what I needed.
Cheers, Hywel