For me the main pain would be Turks with Armenian cavalry:D

I'm more worried about them suffering from a lack of elite units once they expand outside of their heartlands.:p Now I've set the max unit pool for arbitrarily defined elite units to 1 outside a factions heartlands, but I havent playtested it much. But since the AI seems to max out recruitment on a per turn basis I'd guess this means that I'd run into low grade or mercenary armies outside of a factions heartlands, with the specific units being more of a spice.

blacksnail: I imagined such a system. I've just put a regional layer using the Swedish names of the general area (Italien, Flandern, etc, with about 15 general regions for the faction units and a few specific ones for the merceneries). I dont think I'm going to do anything as ambitious with minor tweaks that only are for my own enjoyment, as I want to spend more time playing the game than modding it:)