J seats feel cramped
I am 6ft 200lb and felt confined in the AB J seat on A330. The notice to "don't trap you feet" when the seat is moved forward is for real. But, I had trouble getting my feet up. A large person will have real troubles getting into the seat.
My wife and I were in row 1 E&F, the center seats.
I have flown J on AA 767, 777, 77W and BA 777. QF 747. The J seats on all are better that AB.