None of the text in the "Armor as DR" section addresses how it affects Monks.
I'd imagine that their AC bonus adds to their "Defense" value, but since the list of things to add to your roll for Critical defense checks doesn't include the Monk AC bonus, this means that Monks are easier to score a critical on (assuming the Monk AC Bonus doesn't simply grant DR, which the rules up to that point don't support, and there's nothing to specify what type of DR it would be, since it would be less effective at high levels if just taken as non-magical armor...).
So, I guess I'm asking how the Monk AC bonus is supposed to interact with Armor as DR...
