If your itinerary includes travel to/from USA, then the piece based allowance applies throughout, so you are entitled to 2 pieces

The max weight of the piece is dependant on carrier ( e.g. AA is 23Kg per piece and BA is 23Kg per piece from Feb ). If you are checked through from another carrier , you may be able to get the 32Kg per piece.

To be on safe side and avoid baggage issues, then the safest is to limit yourself to 2x23Kg. When transiting, there should be no issues with checking the bags through to the final destination ( other than in the US due to the annoyance of having to collect bags at 1st point of entry )

I have trouble seeing what is draconian about the size limitation of QF .

Dave