Thank you for the advice. I ended up buying a retina MacBook Pro yesterday at the Apple Store. A little bit more expensive, but I wanted to have the guarantee of an experience with no issues at all when buying a laptop at this price, so I chose to pay the additional premium for buying at an Apple Store.
I ended up going for the 15" low end model, with a 2.4 GHz quad-core i7 processor (I could have bought the higher end model, to be more future-proof, but this one was already expensive enough - anyway, I know I'll end up buying a new computer in the next three years, so I learned that this future-proof thing doesn't work very well with me). I almost went with the 13" retina model, which was the one I was intending to buy. But then the 15" was just a little bit heavier, and the screen seemed to provide some additional and valuable real estate area, which is something important to me. Plus, there's the more powerful processor and the dedicated video card that may end up being useful (and it also makes up for the absence of Iris). It was just shining there, and I couldn't resist it. I found it to be a better value overall.
I wished it was powered by Haswell, as battery life is something important to me. However, Haswell is not going to be available before I leave the US, and this specific model is particularly expensive in Brazil, where it runs for nearly US$ 5,000 and nobody actually buys it. I wouldn't buy it in Brazil even if had a Haswell processor, as I couldn't justify spending more than the country's yearly minimum wage on a laptop.
So far, I found the machine to be just great, the best piece of hardware I've ever owned. It has a beautiful screen, a great keyboard and trackpad and plenty of power to do everything I want and even more. The battery will not last me the whole day, but it's actually very good, and I haven't yet plugged the charger since I've bought it. No issues so far. Although it is just a little more powerful than my latest laptop, it just blows it away in every sense. Absolutely great.