Originally Posted by G-BOAC

I think you need to re-read it again. The difference is whether you do it before departure or after departure. Before, mostly yes (if you wish to remain in CW and pay minimal fare difference...but as the OP demonstrates, T being available but you falling foul of the AP requirements will cost you a lot since W class pricing is used). After, mostly irrelevant (in so far as U class has no bearing and T class will keep the cost down, but W or E being available will still allow you to change, all of them remaining in WT+ and losing the miles).

However, from what I've been told today, maybe, just maybe this might change for the better soon (fingers crossed)