oh, I would prefer if the provinces were already defined; so the characters/players could chose whatever province they think is the best. making provinces re-definable only serves to make things more complicated, even though it can help in power struggles. furthermore, it might eventually make unrealistic looking provinces, such as a "lower greece" defined as Thermon, Ambrakia, Lilibeo for a house which has its main power in Sicily but wishes to get part of Greece.
anyway wasn't it stated in your reforms that "provincial governors chose their capital in the province they are given" or something like that, meaning that they are given a specific province with the set number of regions; among those few, they chose one as their base.

and if control of a region is temporary, how are houses going to maintain the city which they reside in anyway? it could be taken over by a rival house. unless you're suggesting that multiple guys of the same house continuously chose their house's province after their term. but I don't like how that sounds. or if a house could change their HQ location wherever, then I'm fine with that.