After getting the Arca-Swiss Monoball Z1, the next logical step was getting an L-plate for my camera. An L-plate is a camera plate that allows you to position the camera in landscape- AND portrait-mode on the ballhead. Normally you would use the drop-notch on the ballhead to position the camera in portrait mode. This drop-notch is available on most ballheads, but seriously limits the movement of the ballhead, and it puts the camera in a lower (and on most times in an awkward) position.
After serious research, I bought the Really Right Stuff BD300-L. This plate is 100% compatible with the Arca-Swiss system (just like the Wimberley plates).
The following photos show the RRS BD300-L in combination with the Arca-Swiss Monoball Z1.