Award flights - AA / US Airways Amalgamation - cabin classes question

AA's flights to Canada & the Caribbean have Y & J cabins in contrast to most of their domestic services which have Y & F (some doms have 3 classes). QF books OW J pax into J on routes such as DFW - YYC but I notice that US Airways has Y & F (no J cabin) for its PHX - YYC service.

So does anyone know whether the AA takeover of US has / will affect which cabin QF will book OW J awards pax into on US flights? My searches (through QF) for J awards suggest that, although AA now controls US, you will only be booked into Y on US flights, suggesting that the only way to get J seats to YYC is to fly via DFW.

Can anyone confirm this or otherwise? Thanks

Edit: Can anyone shed some light on why a MileSAAver J search on AA would show "Booking Code: O Cabin: First" for US Airways flights - I thought "O" was one of the codes for discount economy? Am I missing something obvious?