The fly in the ointment is that CX departs after midnight SFO-HKG, thus there is not a same-day departure at IAD -- it is the next day. Rather annoyingly AA does check and enforce this. I know this well as I was denied admission to the FL years ago on an F ticket ORD-LAX-HKG due to this technicality -- and what prompted me to get QF Plat status, so I can use the FL whenever I want. Presumably the AC at IAD won't be quite so protective of turf and maybe printing out that rule will work, despite the date change.