I am still strongly in the 2-tile camp for everything, including barns. It only "breaks" barns in so much as it makes the strategy easier, but there are other combinations were this kind of thing happens. For example, being able to put your mayor in to the City of Carcassonne from The Count makes it much easier than originally intended to steal a pennant-filled city.
A clear and consistent set of rules is the most important thing and that means as few special explanations and exceptions as possible. For me, you get that when you think of the castles as two tiles joined together.