A unique feature of classic flight awards with Qantas is the possibility of instant point upgrades to business or first class, when classic availability becomes available. So if you are booked into a Premium Economy classic award and then notice later that a Business classic award is available, you can upgrade instantly by calling Qantas and simply telling them that you want to be rebooked into business now that it's available. I'm unsure whether Qantas charges a change fee for this service (if they do it's 5,000 points) but something to consider.

-RooFlyer88