A quick data point from my side, for my RTW ex-CAI ticket (business class).
1. It's prior to my first flight's departure, and I only wanted to make a date change of my last segments. So I contacted QF by telephone.
2. According to QF's agent, even if it's a date change only, it will trigger a repricing (but likely no price difference as long as they can find a ticket in the same fare group) AND reissue. So it took QF an hour to do this (the agent had to ask another department to do this because they have a better IT system). And the original RTW ticket No. changed to a new one. -->Honestly speaking, I don't quite understand why QF has to reissue in this event. Any one can chime in?

One question:
Is it possible to ask other carriers, e.g. CX or BA to take over this RTW ticket for changes? QF is terrible.