As for JFK-GRU, they force you to sleep entire flight. I don't see any advantage in choosing F other than the boarding pass/baggage tag says F. Besides, every flight in F have been wide open so, there's no guarantee they continue F/C/Y 3-class to operate.
Originally Posted by
number_6
That flight has been operating for years (NRT-JFK-GRU) but uses their worst plane for this route (no shell solo seats on that flight, most of the time). With LAN dropping F service I suppose it will become more popular on AONEx tickets, but it isn't a great flight. JL5/6 NRT-JFK is a lot better, by way of comparison.