Definitive Answer from AA: You must collect your luggage at MIA even if transferring to another international flight when flying AA. I am very impressed with the AA Facebook team - response and obtained a very definite answer - well done!

"Hi DOCGASMAN, our head baggage manager in Miami has responded. They have advised that the ITI program in Miami is temporarily suspended and currently all customers arriving on an American Airlines International flight must collect their bags and pass them through customs then return them at the baggage re-check counter outside of customs, even if connecting to another international flight. They anticipate the ITI program to return to MIA late in Q1 of 2014, but don't have a confirmed date. Thanks for checking with us, and have a great time in Buenos Aires!"