Originally Posted by
raistlin
This is absolutely not true.
A H fare, MXP-JFK, is 1300. The I class ticket you upgrade into is 2000.
Reason why I said
generally speaking, which implies
in most, but not all cases 
Again,
generally speaking, Y+ is obviously cheaper than J however, in several cases I came across, the latter works out much cheaper. The magic world of airline fares!
G