Glofish,
The 510t version at EK now does not have a crew rest fitted so carries 27 more seats in Y class. Its ZFW is also increased to 373t so can carry a bit over 73t of revenue. It does UK, BKK, HKG, ICN, etc. It does not need to be heavier than 510t as to use weight above this would require a crew rest. The one in the article quoting 650 seats is the two class version, which is not in the fleet yet.
The 569t version has a max ZFW of 369t so carries 69t of revenue, and can carry that to JFK and SYD in both directions.
I find it hard to believe that a EK Boeing pilot would be confused about differing MTOWs and ZFWs for the same airframe. Isn't it the same with the classic 772s?
The Don