Sorry, thought I'd specified that it was on AA metal intercontinental (specifically BOS-LHR), my post is indeed very unclear.
Basically I want to book AA J, I think if I use AA miles I will be charged $20 or so. Will QR only charge that if I use QF miles? I would rather use my Amex points than AA miles, esp with the 20% Amex bonus it will be 10k or so less points than AA miles.