Follow-up: my flight back from YVR-SYD was much better than the outbound thanks to a far, far more pleasant crew. What a difference that makes. Food was also better ex-YVR than SYD, though by Row 5, I heard a lot of people (including myself) be told their first (and in one case, second) options were out. I slept a solid 8 hours straight. The purser kindly went through the cabin shortly before arrival and made polite conversation to thank everyone, and when he got to me he noted that it looked like I'd slept well. I said I had, to which he then added, "Yeah, I noticed you were sleeping without a mask at one point but you seemed too comfortable to wake up." My mask had indeed come undone and gotten tangled up in the blanket, and I wasn't sure what else to say other than, "Oh, sorry... well, thanks."
That's a good way to lead into my overall comment about AC on this trip: AC still feels very much locked in the Covid mindset. I've flown 6 long-haul return trips on different airlines since February, and despite being the most recent, AC (and Canada, in general, I'd add) has been by far the strictest in their Covid protocols onboard (even ANA felt laxer). Mandatory mask use is repeatedly announced and enforced (unless you fall asleep on your side in J, perhaps, in which case you might only cop an awkward comment after you wake up), meal service in J felt abbreviated (everything served on one tray, crew that was already quite dressed up in PPE then added even more for meals), etc.
Some may prefer to seek AC out because of this; others may find it a bit much at this point.
Setting aside a few hit-and-miss aspects of crew and service level, the upgrade amounts I paid into J made for a very good deal (all said and done ~$5,000 return with 3 of 4 sectors in J including both trans-pac flights), so I was happy with the overall value proposition and my experience. I can't see myself specifically seeking out AC's product in J, but for those booking PY, it's a very interesting option that provides upgrade opportunity that isn't available on many competitors.