This is a good FAQ, but one thing that's bugging me. This bit from footnote #2:

This would also require some amount of decreased taxes on the next quintile in order to avoid high marginal tax rates, i.e., if you suddenly start paying $2000/year in taxes as soon as your income goes from $19,000/year to $20,000/year then that was a 200% tax rate on that particular extra $1000 earned.

Is warning about an error that almost no one makes, and thus ends up sounding kinda clueless in turn. Current tax codes are already written in terms of marginal rates, so there shouldn't be any risk of increasing income leaving you with less money, as long as we maintain the same basic structure in our tax code while exempting the first X dollars. (Eliezer may know that, but the way it's written still bugs me.)