Another data point - I just upgraded a holiday flight with cash, and they made a point of telling me that they would waive the change fee as I did it within 24 hours of the initial (online) booking.
And a second data point, they then called me back to clarify that as I had upgraded to CW, any future changes would have double the fee (£300pp

).
Perhaps nice cuddly BAH is starting to play hardball...