On the WT and WT+ issue are we confusing "Exit Row" which is what it says in the OP or "Bulkhead".
I take Exit Row to mean you would have to pay £50 to reserve 29B on a 747 because it is an exit row and has more room - but you wouldn't have to pay to be in the front row of WT+ on a 777 because that is a cabin divider and has less legroom..