Not a Plat, and as far as I can see, never will be, but maintain Gold comfortably. Pay for my own tickets and travel both Y and J, always MAN-DXB-TYO. Generally get very good service in Y - agree that, on average it's better in 777 than 380 and that it is also very crew dependant. But usually very good in Y on both planes - comfortable seat reassignments when available, bottled water and treats on request. I only once had some really bad service (777 as it happens), rude and unhelpful, and asked the FA to call the purser. (Purser had also forgot meet-and-greet).
I was my usual polite and smiling self, taking care to apologise for calling the purser from her more pressing duties, but had firm words and - Magic - suddenly I was beset with politeness, care and consideration for the remainder of the flight ... and bottled water and chocolate from J.

I find that travel in Y sometimes is good for the soul (if not the bum) as it makes flying in J (and occasional upgrades to F) all the more pleasurable. Not sure if I'd have the moral fibre to travel Y if I could always afford J, though.
One of my Japanese friends is a senior manager with a major Japanese telecom outfit, which has a company policy of Y travel for staff (but not for directors.) He tells me that he must travel in Y and that his CEO makes a point of always travelling in Y even though company rules would allow him J or F.