Ah Ha.
Is Mach Crit best defined when local flow first becomes sonic anywhere on the wing or over the fuselage?...remembering that camber is not constant, this may well first occur over a very small region and at a surprisingly low free stream Mach.
Or is it better defined as when the pilot is first aware of it's effects?...which of course opens up a whole new can of worms.
Perhaps, with modern aerofoil design resulting in innocuous behaviour at the classic definition of MachCrit, these numbers are no longer quoted in their sales brochures and Mmo is the primary number of interest.