Another wrinkle in the Qatar lounges issue (unrelated to Virgin) is that in SYD their F passengers have no F lounge to go to and get directed to the NZ Business Lounge, which in itself is not awfully busy with just a few flight departures including the 2100hrs Doha one.
The NZ lounge is a pretty solid Biz lounge, but nothing approaching F I can assure you, with the catering winding down mid-evening.
Apparently the QF F lounge closes around 2000hrs most days, and is in any event a very long distance from the QR departure Gate 61.
So no joy on the horizon for QR premium SYD pax it seems.
No point getting to SYD extra early to enjoy a truly F experience unless you can wangle a trip to QF F (if you have requisite status) and are prepared to walk half a km+ to the QR departure gate!