Definitely no upgrade voucher, that's far more valuable than the 90 minute PEY to Y downgrade!

It's a shame how CX likes to have it both ways with PEY; market it as a differentiated experience, but for regional flights there is really zero change to the soft product and CX feels fine swapping planes willy nilly witbout need to take care of pax.

You will be entitled to the fare difference, which will be peanuts (literally maybe 20 USD, possibly even less) if you're on a connecting flight segment as part of a longhaul. I think your best outcome is to get a thousand or two AM in compensation. It really rubs me the wrong way how CX so shamelessly markets the product but treats it like a joke regionally. It's like they're laughing at you if you're dumb enough to believe the soft product hype regionally.

Update: Carrie so, I think I read your post wrong. Are you VOLUNTARILY switching to an earlier flight? If so you most certainly aren't entitled to anything! PEY doesn't run on every flight HKG to TPE and if you want to swap into a non PEY plane then you must accept to sit in the lower class without any compensation.

If it's forced upon you, you are entitled to something small. Unlime what you imply above, the upgrade voucher is definitely not "small", and if somehow they give you that I would shutup immediately and take it! You can use them on longhaul segments. I'd be shocked if they gave that to you.