My $0.02. I have flown LAX-SYD in both J and Y. I have not flown it since Y+ came along. My wife and I flew ATL-AMS on an A-330 in July, and I upgraded us to Y+ for the eastbound (overnight) leg. I do think there are advantages to the greater legroom for sleeping, as well as getting in an out of a window seat.

I am 6'1" and have flown many TATL and TPAC flights in coach on lots of different types of aircraft, and I am used to it and usually sleep as much as possible. But a little extra legroom goes a long way.