I have the Z1 and use it with equipment as heavy and awkward as a Pentax 67 with a 500mm lens and 2x. Properly tensioned, the elliptical ball of the Z1 allows me easy intentional movement of the camera, but no creep upon release or lock down. I avoided the screw version for two reasons: the screw is not captive and so is in danger of being lost in travels; the knob itself is difficult to pack in such a way that it is not vulnerable to damage in packed luggage. I have the flip lock version. To say its operation is not intuitive is an understatement (its operation could be used as an advanced mechanical aptitude screening test); nevertheless, once understood, it’s fast and easy to use and has the advantage of being easily adjustable to various plates. The RRS lever seems superior, but I chose the Z1 over the BH-55 because the Z1 has an elliptical ball, it’s lighter and less expensive and I can always add a RRS lever if needed. I’m quite happy with it.
Tom