I see your point, especially on the border towns thing. I do think there's going to be enough rewards for regular city sieges to be rampant even with something like this, though. Dragons, on the other hand...meh. I need to see a fully workable concept with creativty before anyone can sell them to me
Indeed, dwarves should focus on having really good siege and pretty good defense in my opinion-a sort of balance. I see them being more defensive with little cavalry and slow movement speed, personally, but that's my take on their race as a whole. Probably biased from LotR.