Y is not that bad as long as

1) You get an aisle seat to provide for easy escape
2) You don't get someone huge sitting next to you (and given how many there are these days it's a 50/50 chance) and/or someone who thinks part of your seat is his
3) Get a bulkhead if poss for the legroom but you may get a screamer for your trouble

I have now taken to booking Y out to the US (day flight) WT+ back MFU'd to Club (night flight).

Bottom line, Y for a day flight is ok (ish), for a night flight it's not advisable so for HKG, either drink a lot or take something for the pain.