I'm afraid of these.
Just a quick thought: what kind of society would we live in, where workers have to produce an extra four hours a day just to compete? Combine this with an escalation of workers (due to globalization), and the supply of labor increases, without necessarily increasing demand.
So the quality of life decreases for the majority of people, all because science comes up with yet another drug, not unlike these.
Now don't get me wrong: I'm a science nut. I dig all things tech. However, I'm also pragmatic enough to realize that just because it's science, doesn't mean it's good.