The Q Bag Tag is basically an rfid chip embedded device, that when you check your bag, the id is read and then programmed into the system so the bag can be routed / traced. So in theory it shouldn't matter which Q-Tag you use, as it would be read every time you check in.
But I am not sure if Qantas programs additional data onto the chip such as your frequent flyer number or name or has already stored the rfid numbers in your FF profile or simply connects the rfid id to your account each time you check in.
You could loan the device to your friend, let them try it on a flight. Worse case scenario at check in the system will reject the Q Tag because it doesn't match the name on the booking and print out an old fashion "temporary" tag.