After a bit of a delay, the metal finally arrived to make a set of plates for the two quick release bases.
Three have a 1/4UNC screw, two for cameras, one for bins, and the other one is 3/8UNC to fit a base I made while waiting, for a Nikon EDIII field scope.
Seems these are lever operated Q/R's are gaining in popularity as I see Markins are now producing their version, albeit at the moment only as an option with the M20 ball head. Link
http://www.markinsamerica.com/MA5/M20.php?req=M20LK
Don