I agree with this, but I also think that our big important decisions probably determine a lot less of our success than we like to think. A very large part of success probably comes from either the sum of our smaller decisions, or from decisions that didn't seem too important at the time but ended up making a very large difference in retrospect. The experiment I mentioned has raised my awareness of this.

I also think the big decisions are the ones it's hardest to apply extreme rationality to, both because the emotional stakes are so high and because by the time we make them we've already made a pile of smaller decisions that have tipped us in one or the other direction. See http://www.overcomingbias.com/2007/10/we-change-our-m.html . I predict not-significantly-different statistics for people who have trained in extreme rationality, though without a very high degree of confidence.