I have flown both Y and J on FI, and I was very underwhelmed with J and quite impressed with Y. What I really remember is how bad the food was in J, just awful, all three times I was up there, whereas I enjoyed the food in Y, though all booze is for sale only.

I'm booked on the inaugural flight out of DEN in Economy Comfort, so that will be a new experience, but so will be flying on an FI 767. Have NO idea where to sit, and can't find it on seatguru or seatexpert, either.