It used to be very difficult getting long haul business class award. My wife booked a SFO-HKG round trip business class upgrade to return for the Chinese New Year. She booked that in December, and was just an Asia Miles member. It used to be almost impossible for that route until CX added the second flight in October.

My feeling is that booking on web does not distinguish an AM member from a MPC member, but definitely MPC members will get higher priorities when they call the MPC hotline.