Thank you all very much for taking the time to reply - there's an awful lot of useful info here.
The ball head is the most important component of a support system. There are better places (eg: lens and body plates, clamps, flash brackets, macro rails...) where one can save money. I recommend investing in a top ball head, then saving elsewhere.
Yes, absolutely. I can't quite stretch to Linhof, but that aside, I'm willing to pay what it takes. I just want something that really works for me. (I already have a ballhead that doesn't...)
I've read the thread carefully several times now, and what I keep coming back to are the recommendations for Acratech. Strong but lightweight and easy to keep clean are excellent points in favour, and I like the gimbal/leveling base trick, although I don't know how much I'd actually use it.
I'm willing to carry as much as I have to, weight-wise, to be sure it'll hold my gear properly, but once that's given, the lighter the better. And the place I'm most likely to use it is on beaches, so while I'm rather hoping I wouldn't drop it in the drink or mud, having something that will forgive that if it does happen also appeals. (Also, I can be a bit of a klutz, so.)
I'm specifically considering the Acratech GP
, which btw does have a tensioning knob (re: scottburgess's caveat about having to "crank on the tightening knob to really lock it down", which would be an issue because I don't have particularly strong hands).
Acratech don't however do custom L-plates, and Hejnar Photo don't seem to do them for Canon. My local bricks-and-mortar camera shop could order me one, but I didn't quite catch which brand it would be - Kirk, I think.
Would the Acratech GP be a good choice, do you think? And if so, where would I best go for my L-plate?