I'm an Aussie moving to London in July and have been doing the sums on this for a while now. The earn rate for BAEC is so low for most flights in discount Y that I am going to stick with QFF on all my flights. I am unlikely to do enough flying for any status so it is all about the points. I'll have a BAEC account for credit card and Tesco points but all flying will go to my QFF account because the earn rates are so much better.
I would only consider BAEC to credit flight points if I was doing enough flying that status was realistic (which may happen) or a lot of my flying that was not in discount Y, unlikely to happen.
Jase.