"I think the big winners from this are Silvers and early booking Golds. Late booking Golds lose out a little bit, while Blues get totally stuffed".

This seems spot-on from comments and from how the system is supposed to work. I'm a very-late-booking gold so generally hacked off with the change. The balance in general has moved benefits away from gold card holders to silver card holders which seems odd. I think the real driver is simplicity - its an easier to manage process for BA - rather than rewarding status/loyalty which it patently does not do.