Wouldn't that be a domestic flight, so no LAGS?
It's a domestic flight but in an international airport (or for ADL anyway, "section").
Since it's run through the international part, it's all international rules, which means no go on LAGs.
You'd think that all governments and especially flights etc. with domestic-international sectors (e.g. CX105 HKG-ADL-MEL, QF82 SIN-ADL-MEL) would make appropriate arrangements for LAGs so that those that purchase (or carry) "secure" bags through SIN (or HKG) can still carry them into Australia into final destination MEL.
Good to hear your upgrades came through. You did pretty well, although mustn't be all that popular sector to upgrade, or just not enough upgrade requests, or the QF upgrade generosity continues.
Skyslopes
IIRC the old LH J class (not sure how many of them are out there) also has lie-flat - not fully flat - seats, plus flaky IFE (non-AVOD). I can't remember exactly what it is (I could look it up....).
So it seems QF isn't the only one in the air with lie-flat J seats, but lie-flat is definitely yesterday's news. To quote one of the LH reps from the Star Mega Do, "We were very fast to implement this technology but now we need to reconsider our position; it is not that it was a strategic blunder, but it's just that we went fast and now times are changing."