i can answer from my prospective , although i am not as heaviuly involved in the gameplay side of things as i would like to be at the moment due to RL commitments.
The AI have no problem with terrain so far there is however some differences that some may find either beneficial or non beneficial.
The main one being that because the "terrain" has a roadway lod , vehicles now travel at a nice speed .
waypoints are as normal and ai respond accordingly , the ai recognize the change in terrain and if you have shaped a hill or berm they will treat it as such , thus climb the slope again because it has a roadway lod they wil climb it a little faster , although at a certain angle they will default to a slower pace as per the norm.
there are many many aspects of this which would enhance game play at the moment there are also many finite details which are not so apparent when playing on "normal terrain" that need to be replicated byt our terrain, this will take many hours of testing i am sure.
again this is my experience from the little time i have to test ,using RTE and spon_terrain and dbo_tiles.
for me in its current state it is the ultimate single player create a war and surroundings and go that i have ever had the pleasure to spend time with.
DB