Yeah, I read the first economist article and I have two objections to the Brazilian policy, I'll start with the minor problem. The minor problem is here:
"What stands out from a decade of debate about affirmative action is that it is being implemented in a very Brazilian way. Each university has taken its own decisions. The federal government has tried to promote the policy, but not impose it."
-I don't find that very strong. Either you believe - and have good reason to believe - that there is a national problem, and you introduce a national solution (of course, you can make a mathematical formula for these quotas where the specific racial distribution of an area yields a specific outcome in quota) or you don't. Now the federal government is just saddling up Universities - that should be thinking about education and research - with a highly political problem. Better to impose your view and make it clear that the government, and not University boards, are the one responsible for the decision.
The main problem, however, that I'm having with any AA is that I believe that society in itself is progressing to solving these problems itself. In the 1960s, the Dutch government still fired any female civil servant who got married. I worked in a building that was built in roughly the same period of time, and in the old setup, it had toilets marked "men", "women", "gentlemen", "ladies". The latter two were reserved for all those who had been through University. How times have changed.
I recently heard a story about a prize being awarded to "best non-black runner" in a marathon, because the sport had become so dominated by people from - I believe - the eastern part of Africa (apparently their genes give their body a very small edge that on average allows them to take a few seconds of the race). Well, as a non-black myself, I can tell you I don't have the slightest interest in who won that "prize". If people from Eastern Africa are good runners, then I'll happily watch them be the first to cross the finish line.
Meritocracy is the answer, and abolishing discrimination, not inverting it.