lorax - 1:33 pm on Nov 16, 2012 (gmt 0)
I don't have a clear answer for you but technically I don't see a reason WP can't do what you're asking it to do. Especially since you were able to do it with the previous theme.
I am curious why you're using tags to drive this. I assume there's some need for the flexibility the tags offer over evaluating for categories and delivering a specific theme.