I find the messenger so amazing (alright, the whole mod is amazing). It have made life so much easier, and I find more realistic, that I don't have to travel the map, just to recruit a Surgeon. I send word out and they come to me.

Low Priority suggestions, but might as well suggest it;
I like to start playing on default with all mods, as I assume that is the settings the creator find most balance/fair. If that is the case for Diplomacy, I do find it more balanced for messenger to cost 500 gold and can take up to 7 days (there is a chance the messenger have to travel across the whole map, and let's make it worth their while). As said, just a suggestion. Easy for everyone to change as preferred.