Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)

There's no reason why you can't open a BA Avios and/or avios.com account also, and earn Avios from a U.K. payment card, Tesco shopping, etc., if you ever expect to need award travel from the U.K. to elsewhere in Europe. Avios can also be useful for short- and medium-haul nonstops on AA and AS within the U.S. (including between the West Coast and Hawaii). Many of us have accounts in several different FFPs.

But it does sound like it makes sense for you to pursue status with AAdvantage.