When I mentioned "I'd love to see post-booking paid upgrade 'offers' on Qantas website like BA do," I should add that I was talking mainly about long haul flights here.
And no, I am not particularly interested in it being a good offer, although a good offer would be nice - it's just nice to have the option to easily upgrade a flight online with money (even if it costs the same as the fare difference anyway, or even a bit more), without having to cancel the ticket and book another one (which to me goes into the 'I can't be bothered' basket because I'm lazy).
Qantas will make more money out of me if they offered this option, because on BA, I do a random 'gradual upgrade with money' online quite often.