Just wanted to report back that cootramo worked out pretty well for us. Pre-booked prior to arrival in Rio and proceeded outside with a printout of the confirmation email. The driver was clueless and spoke zero English, but eventually figured out that it was a web order and that he should start driving. It was funny though, when we found him he opened his trunk and motioned for us to load our bags ourselves - welcome to Rio! At least we made it to our hotel safely and with all our belongings so we can't complain.

Took another chance on cootramo for the return to the airport and this time the experience was far better. Driver was ontime and even came to the lobby to get our bags (it was raining outside). He spoke a little English and already had the web order number so it was easy as pie.

I'm sure a yellow cab would've worked fine but it was nice to pay via CC and not worry about finding an ATM (harder than I expected) or getting a horrible exchange rate from banco safra.