AnWulf, I think what Sergio is saying is that all of us can call ourselves americanos meaning we are from the Americas, but when you are specifically talking about the country you come from you shouldn't say americano in spanish, because that does not refer to a citizen of the United States in spanish, even though in english that is alright to say.
I'm Canadian, and studying in Chile right now, and it really really bothers me when I read academic texts here when they refer to citizens of the US as "norteamericanos"!!!!! ARGH Sergio, can you please tell your paisanos and the rest of South America the US citizens should not be called "norteamericanos"!? Norteamericanos are anyone from Canada, the US or Mexico...so when referring to a person from the US, it should be "estadounidense" not "estadounidense o norteamericano"! This is more aggravating to me than the debate over whether US citizens should be called Americans. I like Hacovo's idea to say U.S. Americans. I always try to avoid using the term Americans when referring to U.S. Americans in my writing to the point where it is probably difficult to read.