When on a hydaulic brake coach, M&G simply adds an air compressor & accumulator to the package to supply air to operate the slave unit in the toad. Other than the sourc eof the air pressure, it is supposed to operate exactly the same.
M&G also has a variant of their system which works with coaches that have air-over-hydraulic brakes (older Safari chassis). It uses the chassis air system combined with a hydraulic brake proportioning valve. Sort of a hybrid between the air model and the no-air model.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL