To update this, I received the Markins ballhead with the Quick screw clamp. It's actually faster to operate than either the Markins lever or the RRS lever clamp. It takes only one to two turns to release the camera L bracket or lens plate. And like any Markins product, the movement is silky smooth and more secure than the lever IMO. Very glad I made that decision.
If I had the choice, I would exchange the lever clamps on my Feisol and monopod to the Markins Quickscrew.

