I am flying on QF23 next month connecting from Melbourne (QF408) and I'm wondering if these domestic connections aren't part of the issue?
Josh2, a very good point, because when I looked it up, QF408, the 0700 hours MEL - SYD (due into SYD at 0825 hours and probably the latest connection on a traveller's PNR that is 'guaranteed') was cancelled one day in the past week and badly late on two other days (including one day when it was an A333 that went on to form a delayed 1015 hours SYD - SIN, QF81).
Given QF does not operate own metal nonstops MEL to BKK or vice versa, one would expect quite a lot of connecting passengers from MEL. That's certainly been my experience on most international flights ex SYD on numerous airlines, even if these days there are more nonstops out of MEL, though still not to all popular destinations. Quickstatus sums it up well.
You may not want to get up earlier, your travel may not be changeable without a fee or there may be no seats in your fare class, but perhaps if you want a less stressful trip I'd be inclined to go up on the 0630 hours if that suits. But we all know how crawling out of bed at 0400 during a Melbourne winter is challenging.
That this flight (the 408) had problems three days out of seven does not mean it will when you travel, but it shows a trend.
The Flightstats site suggests that on its last 61 trips, QF408 has been 'late', 'very late' or 'excessively late' on 14 occasions and cancelled on another five.
Also states that QF23 has been punctual only 27 per cent of the time in its most recent 59 flights, with an 'average delay' of 57 minutes.
It never defines 'late' but I suggest it means 'more than 15 minutes late arriving', so not a great record is it?