You might also consider the Manfrotto 055CXPro3 or 055CXPro4 which I think are the successors to the 055MF models. I have the 055CXPro4 (bought from RGB Tech) and it's a lovely piece of kit.
I discovered a range of ballheads made by a German company called
FLM that seem comparable in performance & build quality with Arca Swiss, RRS, Markins etc. I think that
Speedgraphic is the only place in the UK that stocks them. The model I have is the CB48FT which cost about £124 to which I added a Manfrotto QR plate. Aside from being silky smooth etc etc, the feature that attracted me was the ability to lock the ball to limit movement to one axis. I'm very pleased with it - well worth the £££ imho.