The $125 is probably fair UNTIL you think about the AU$75 that QF is going to add on as their "agency" fee to make the changes.
The inclusion of MEL-PER in the restricted fare will be painful, but Adelaide does have a new terminal opening. (My current xONEx had MEL-PER, PER-MEL, PER-MEL, PER-SYD) Perhaps also why QF haven't added a PER-AKL flight to compete with AirNewZealand's daily non-stop. Might be too useful for the various OW fares..... especially for tickets purchased in SEAsia.
Surprised they didn't include PER-DRW in the restrictions as it is further than PER-MEL
Your opinions probably vary.
Happy wandering
WF