I use the Arca QR that came with the Cube. For the rails I use the RRS MPR-73 on both the bottom and side of the Alpa STC. These are a little big but they have an anti-twist bar on them and are rock solid on the camera. On the rare occasions that I carry the STC for handheld I may remove the side plate using my Alpa tool but for 99.99% of the time it's left on the camera.
Hope that helps.