The October 2010 changes introduced tier bonuses for BAEC Silver and Gold card holders travelling on AA and IB. So with travel on AA, we (as BA elites) now earn an additional 100% miles on top of the base mileage and cabin bonus (where applicable).

Cabin bonus remained the same at 25%/50% for AA metal/AA code in business/first class respectively and 50%/100% for AA metal/BA code.

That's the science bit - booking BA codeshares on AA still presents a challenge as this can only be done when combined with BA TATL sectors.

Hope this helps.