To follow-up on this, I did in fact go on a 2 week set departure Brazil tour with Eduardo. Here are my personal impressions:
The good: the tour was highly successful, and I would rate Eduardo’s birding skills as excellent. He also makes the extra effort to get the bird, when necessary, and he is enthusiastic and generally in good spirits. I was also impressed that he had recordings of some mammal calls, and was even able to call back marmosets that would otherwise have quickly fled from us.
My concerns: he can be somewhat inflexible, focusing on birds he thinks participants ought to see (or that he wants to see) rather than what they want to see. On occasion, important logistical information was not communicated to us in a timely fashion. Occasionally he was irascible without apparent reason. Also, I was overcharged for laundry at one hotel, and he declined to translate or be my advocate in the dispute, he just stood there waiting for me to pay. In certain respects, he seemed to play favorites among the participants. His English sometimes fails him when having to quickly describe the location of a bird.
I think most of the participants were happy and would go on a tour with him again. Personally, I would think twice before doing so for the reasons mentioned.