Originally Posted by
hdogan
Knowing SQ, they would most definitely prohibit it. Actually, they would prohibit it in any airline, and SQ is even more defensive of their premium cabins. Furthermore, PE has fixed armrests, you'll actually be more comfortable sleeping in an empty row in Y, which you're very likely to get.
When I agree that SQ is really defensive, the rest of the post above is really incorrect.
As soon as the moving will not compromise the weight, I don't see why any airlines can't allow that. In fact, I have done this before, on UA where I was seated at non-lie-flat business. I was allowed to move back to E+ and got the whole row by myself. Also - if you indeed have the whole Y row, your experience would be better at PE.
I honestly don't know why
hdogan would say something like that. But keep in mind - always ask before moving.