If timing and tight connections are an issue, be aware that QF is having dreadful reliability problems with long hauls leaving Oz - industrial action. QF 1, 5, 31 and their returns are hit hard with delays sometimes 4 hrs and occasionally 22 hrs. Check the QF web site (departures) for determining a trend.
Strangely, these all originate in SYD - given the QF 29 operates MEL-HKG-LHR, has there been any issues regarding MEL originating flights?
Dave