I was on an HKG-SHA last week (fyi, this is consistently the single most elite heavy flight in the whole CX by far). ~30 out of 39 in J alone were DMs so I was asked if I could move to the PVG flight (with Aria) which I declined. The check in staff at the podium acknowledged that they usually would not ask DMs but the system prompted them to ask every single pax for that day. I asked and there was no cash or mileage compensation (so I politely declined )

Fyi, I didn't get my first meal choice as they only had 13 of each loaded. I tried to probe a bit with the crew as to how they maneuvered around the cabin (as I was sitting up front but they came to me quite late), but they just shrugged it off and told me 'we are full today' blabla. oh well