What specifically is the problem with transfer process in SYD, MEL and BNE?
Compared to Asia, it can be very slow and airports aren't designed as well as an transit point. Having to re-clear security, adds to the process which isn't done in some other transit points.
I find the Australian transit system I've used many times in BNE,SYD,MEL to be better than what I've encountered in SIN,DXB. Reason I say that is when you are re-screened and pass from arrivals into departures, you only have to queue with those that are in transit ie not the whole planeload. As long as you remember not to be #1 through the system in which case you get the "random" explosives test. With the system where arrivals and departures are intermingled and you get re-screened at the gate then you are queueing with the whole planeload.
The bigger problem I have with the Australia transfer system is that the last 3 times my luggage has gone AWOL for 1-2 days!
I'll probably try DXB-AKL once, and then go back to the A380 + extra stop in Australia + QF status credits + points