After trying a variety of combinations (waaaay to many in fact), and having some stability problems, travel problems, etc etc I recently went with a new setup which I am VERY happy with. It's not cheap, but I think it will last many years.
Legs: GITZO GT3540LS
Head: BH-55 from Really Right Stuff
Leveling plate: Manfrotto 338. This is the micro adjust one, only put it on when doing landscape pano's etc. I am considering getting the Gitzo leveler for the tripod at somepoint.
I went this combination for rigidity, but also for travel by plane. The legs compact nice and short, but the whole setup is very solid even with a 500mm Lens.
Sitting on top of the ballhead I also use a Manfrotto 300N Pano Base, and a combination of a RRS slide and clamps as a Nodal point/levelling/rotation setup for doing Panoramics.
Regards
Mark.