Funny you mention this - in all my years of flying CX and literally hundreds (if not more) of flights as a Invitation member I have only received 2 "space available" upgrades not due to overbooking - one was HKG -BKK when they launched the new J class seats and the other was JNB to HKG - never could figure out why as the flight was not full in any class - GUess JNB ground staff are just generous.

Thank you JNB! Keep it up!