From personal experience I am pretty sure PE china southern would be very similar. Yes no additional width, increased pitch, extra bottle of water and maybe 1 small extra item added in the meal.

I am split on this story. Behaviour was horrible by the passengers. But I am equally disturbed the airline did not straight away offer the refund before boarding (After they knew the aircraft change) or when on the plane before their complaints. The product advertised clearly was not what they got. If they had been told 100 USD extra for a bigger pitch seat in economy then that would be fair. Upgrading to business class would not be unheard of in these cases in many airlines of the world. Definitely as I fly CI premium economy all the time now for long haul flights I would expect at a min a refund (cost of PE over cheapest economy is double the price) or an upgrade to Business class (but I wouldn't push it) if I was swapped on to say an A330 to BNE which has no PE.

I think why CA crew were tough nuts is because this is very common kind of issues for them. I have been on CZ flights from AMS to CAN where economy was fully packed and PE was almost empty. Some passengers decided to just upgrade themselves because it looked better. Also I had a friend a long time ago who admitted to just walking into business class during the flight and sitting down and enjoying herself on 2 occasions. 1 time she was there until landing and the other time it took a while before the crew asked her why she was there.