Oh I am a sucker for AUs. Don't ask me why though. I just like playing with different ideas and character versions. I still love the original characters the most though.
This worked for me because it was still Sam and Dean and you could see it despite it being AU.

As for the role reversal... I have so many words in my head why I it made sense to me that it would be a complete meta post I think. But ahania has one here that kind of describes my thoughts about that in a way.

Oh well I liked *this* angel ;)