Actually this is a question about EU regulation and has little to do with QF. In my experience the Oneworld airlines comply with EU law grudgingly and push the regulations aggressively (particularly in the case of BA, which routinely claims that flight delays are due to weather, and thus exempt, even when they have no plane or crew available to fly that specific flight). So, don't expect QF to go above and beyond, and if it does, it will deduct the 600EUR from the other compensation that was already paid. So, my guess is that unless your total comp is under 600 EUR (highly unlikely), there is no relevance of the 600EUR payout. Technically if your flight operated, then no compensation is due, never mind that it was "only" 3 hour notice, so QF is being much more generous than required to be by law or regulation.