I have the Sharpes one-piece which I use on big fast rivers.
I also have a light collapsable (Vision) one which I carry for smaller rivers if I don't think I'll be using it all day. It's very good, and I'll usually take it with me on occasions when the one-piece feels like a faff if I'm not using it all the time.
I try to always wear mine on the downstream side of me. So I switch it around if I change banks. This means when I let go of the stick it is always out of the way below me. I don't have the stick lying across my legs where I may trip over it, or where it will tangle the line. I have it on one of those hammerhead retractors which works well, and gives me enough leeway to switch hands if I need to (hardly ever).
I really like Hamish's point about not relying solely on the stick. For me a stick is for stability when taking a step. If I need my hand on the stick while I'm casting, I've gone too far
Similarly, I don't really want to have to put all my weight on the stick, for same reason I don't want to stand on one leg in the middle of the river.
As I get older, the stick seems more and more useful when I'm climbing out up high banks.
W.