Ditto for what Cigar and Channa said.

Have you considered going with NH or SQ and banking the miles back to UA while continuingf to CO for domestic and Europe flights (which is where the excel IMHO).

Also there's some good posting by Heathrowguy a few months back detailing why the AA/BA FF mileage restriction exists. Quite interesting if you're into that kind of thing... which I am