This is an interesting thread. I faced a similar decision last week, although made my conclusion very quickly.. Day flight to UAE: £700 r/t in WT, £2.2k r/t in WT+. I run my own business, so went for Y. First time I've flown Y on BA for a few years. Had a bulkhead seat. I am skinny and couldn't believe the seats were so narrow. Luckily I had an empty seat next to me and great crew.
However, here I am, I survived. It was perfectly tolerable for 6 hours with a couple of movies. I felt great for saving £1500 when walking off the plane too.
Night flight however, I'd opt for WT+.