I just did JFK-HKG RT and thought PEY was definitely worth the 30% premium over Y CX is charging ex-US. In addition to the extra seat width and pitch, the fact that CX has heavy curtains and actually uses them also makes a difference-- the cabin feels a lot quieter and more intimate. Walking to the galley in Y from PEY, you really notice the difference.
Are you talking about the "main" Y cabin?
I find that the "mini Y cabin" in both the 77H an 77G to be fairy quiet too.
In the 77G with 3-class layout....there's only like 3-4 rows of seats there, very similar to the PEY cabin.