Nice thread. The only thing I can add is that the three agent types seem very "rock scissors paper" to me. One thing in particular that wasn't(?) emphasized (past what you said, econ) is that monks have the ability to convert (a.k.a. kill) ninja and metsuke, which to me is kind of cool (maybe I'm a closet buddhist?).

I am not seeing mentioned here, the very nice effect that high level metsuke can have on town income - put them in towns with your highest income. Hover your cursor over the Tax Rate for a town to see their "character effect". Also of course, use monks to rid your provinces of those insidious christians. But then, these points don't directly impact agent advancement.

RK