I have gone through all of these and god it's a hard decision. For various reasons I have reduced it to 3, be it cost, reliability, little quirks and various reviews the 3 so far are- arca z1, feisol cb-50d and although I know little about the company or their quality third place goes to Sunwayfoto DB44. Is the Arca Swiss Z1 worth the extra cost over the Feisol or Sunwayfoto.? My wife is in America on a shopping trip in about 8 weeks and if need be she can get the Arca or Feisol from B&H whilst there which will save a little.so plenty of time to decide.
I would go for the Arca-Swiss Z1 - given the weight (and cost) of your kit, money well spent, last for donkeys. You could maybe save a bit by buying in the US, but technically it'd be liable to import duty and VAT. Robert White had 10% off recently, maybe you could twist their arms on that one, or sometimes it's a bit cheaper to import from an EU retailer, depending on the exchange rate.
I've not tried the Feisol CB-50D, though it looks tempting. All I would say there is that I've found the larger versions of good heads are not automatically better, despite the theory that they should be. SunwayFoto is a very good, high quality brand, but I believe the DB44 is officially discontinued. The UK importer (CameraGearUK) bought the last 200. Apparently the DB44 was too expensive to manufacture, but its replacements are not
quite as good (FB-44 had some issues, now sorted with the FB-44II).
Have you tried the Manfrotto Hydrostatic? Not the sexiest looking head perhaps, but with an Arca-Swiss clamp it takes some beating and the price is right. You need to try them with your (long, heavy) gear. Things are not quite the same if you test with a lighter load, when it comes to adjusting position accurately off-axis and locking down.
Have you seen the Traumfleiger tests? In German, and web translation is more entertaining than useful, but you'll get the gist of it
http://www.traumflieger.de/desktop/ballhead/ballheads4.php Some good tests on DPReview also. There aren't many good reviews of this stuff on the web - most are from bloggers...