Homebrewer, no, I said that when I use the ATM I get the interbank rate and pay an additional flat fee, so as long as I withdraw the daily maximum I do better at an ATM than I would exchanging the same amount of US $ at a cambio. My credit cards charge an international transaction fee and don't state that they exchange at the interbank rate. So I don't use them when I travel foreign except in an emergency.

Oh, and telling your bank not to accept charges outside your travel dates works up to a point, but if someone is trying to run charges against your card your bank will still cancel that number and issue you a new card. This is a PITA that I prefer to avoid.