I have an Arca-Swiss Z1 (it's flawless) with a 1/4 thread. I plan on getting some type of quick release and have narrowed it down to three types: 1: Arca Swiss Flip Lock QR, 2: Really Right Stuff leaver release or 3: Kirk Enterprises Quick Release (with nob).
The Arca-Swiss looks elegant, but is considered finicky to use and potentially vulnerable to damage.
The RRS looks excellent, but their comment not to use with Monopods (I'd like to use the same mechanism on my monopod too) makes me wonder about it altogether.
The Kirk enterprises seems the simplest, but the half rotation to drop in might be precarious in some circumstances.
I plan on retrofitting an older Gitzo tripod, a Gitzo monopod and the A-S Z1 on a Gitzo 2541ex (also perfect), so this will represent a significant investment in money, not to mention the camera plates, etc.
I now have a love-hate relationship with tripods that I'm trying to shift further towards love by simplifying set-up.