So, well done Qantas. The flight arrived at a couple of minutes after 05:00.
Virginblue makes a good point. It may be a 17 hour flight but QF9 originates in Melbourne so add on 4 hours for that part of the trip, plus time on the ground at Perth.
Ignoring time on the ground (Perth & Dubai) and the total flight time of both routes is more or less the same, at least for the Melbourne passengers. One big difference though is the number of passengers. The A380 service has 480 seats and the 787 has 230 (both numbers approximate).
So I am a bit puzzled re advantages to Qantas with this flight change.