Not been to Rio yet so can't comment on first hand experiences.

What I will say though is according to some guide books (mainly USA publications) I have read concerning safety in Buenos Aires. If I were a tourist, I would never leave my hotel room if I believed all what they said.

I do believe that Rio has worse crime statistics than BA but I guess most of it centres round it's own citizens and a very small percentage concerning tourists and most of them might have been caused by carelessness and not taking the necessary precautions.

I agree with James S, enjoy. ^