I fly across the cabins usually on routes of this length. As first world as it sounds, First Class beds will actually deliver a 'proper sleep' in terms of comfort. J is great, and I can still get 7-10h in on those beds but the comfort of F is far superior. When coupled with the quieter cabin and privacy doors I could not let that kind of fare difference pass me by. Sadly I usually use miles for F since its so expensive ex-SYD.