It funny the experiences one has when shooting zillions of weddings, many at a dead run, with little time to ... well ... take your time. My Arca B1 has been locked up more than once by 2 different assistants, and I have an Arca QR that simply fell apart, springs flying everywhere.
I guess Arca and I don't get along to well.
In contrast the Gitzo mag. ball head and QR used for maybe 5-6 years now has never been a problem ... and I like their slide-in QR because it accepts both Arca type plates and the Stroboframe plates used for QR on flash brackets and camera plates on my Metz potato masher.