Overall I like the province investments as larger decisions about a province, in comparison to the territory level decision of buildings. However, the four choices are a hold-over from the original release which was much more focused on the four traits (and their associated mana) - martial, finesse, oratory and zeal. The effects feel a little shoe-horned into those four categories. For verteran players this is not a big deal, but for new players these are probably not very intuiatve. I wouldn't mind a minor update to the system that re-casts these around some other organizing principle. Depending on the principle, this could open up some design space, as you would not necissarily be restricted to exactly four slots.