I just took delivery of my Acratech GV2 ballhead with levelling clamp. It is an awesome little ballhead but with big credentials. This ballhead weighs less then 500g but can support over 11kg at any angle!
It is very easy to adjust, smooth to use. They don’t come cheap but you do get what you paid for.
In Australia, I got mine from PhotoVideo. I highly recommend them, great service and delivery from Greg.