Very interesting system !
First remark : Will we be able to change our province policy in another way than destroying it. I mean, what could possibly forbid to have an "Autonomous Province" or "Client State" and initiate a change to make this province a fully part of the country as a "Colony" or a "Direct Province" ? Maybe should we only back on Tier II if we decide to make this kind of shift, beceause Tier I is only meant to install our presence in the first times of occupation. Anyway if we can't do that for some gameplay reasons I will completely understand, this system is already very well done and it should work very well in game.
Second remark : It's about the effect of the "Colony" policy. I think you should add +1 Exp troop bonus to this policy for the Greek states. Baktria, Seleucids and even Egypt have installed military colonies in their country to hellenize (i don't know if this word exists
) it, with more or less efficiency. The bonus would represent well this historical reality.
Third remark : Why didn't you add Greece in this mod (well, there is only Thrace but Thracians are only barbarians
)?