I am an asylee from Brazil. My asylee friend from Colombia went to Brazil on his RTD to meet his family there. And he DID NEED A VISA. Even though he would be let in Brazil with his Colombian passport, he chose to get a visa stamped on his RTD. He told me that he was treated very well upon his arrival, but when he was departing from Sao Paulo the same hapenned with Varig Airlines when he showed his RTD- The had no clue and had to call a supervisor. I also know that Argentina DOES require a visa because one time I almost went there to meet my parents. But then gave up because they gave me too much drama to issue my visa and I decided to go to Mexico.
Here is my experience going to Mexico. I went to the Consulate in LA and applied for the visa...they said it would take at least 4 weeks to process and someone would call me to let me know the decision on my application.....I never got a call back....Maybe they have a week of 300 days in Mexico.When I called nobody knew about my process, especially because they give u no receipt of anything..I mean, it is a total mess!
...So I decided to use my RTD WITHOUT a visa, also took my Brazilian Passport just in case because they do not require a visa to Brazilians...Thankfully I DID NOT need to use my national passport because they treated me like a US citizen and did not care that I did not have a visa. I went there twice using the same method and was never stoppped from entering Mexico.
Just be aware that Mexico, Brazil , Argentina ,all those consulates will give you the worse time to issue your visa. Brazil is the most organized one ( not because is my (ex) country)!!!!!!a lot of Bureaucracy!!!!!!!!!! Good luck and have fun dancing your samba/tango/mariachi!