While I don't fly internationally nearly as often as I used to (1x or 2x a month from EWR-MAN for 2+ years), I don't think J or F is really justifiable, unless a solid corporate contract with deep discounts is in place. While F or J is obviously a much better experience, I don't find myself appreciably more rested than after a flight in Y. YMMV, of course.

Would I like to fly J or F on long flights? Of course, and I upgrade whenever possible using miles, but seeing the hit on my P&L every quarter for Y travel (All of my employees travel almost weekly), I wouldn't even want to venture a guess as to how ugly it would be with J and F fares.