Alright, I'm going to allow re-flavoring your attacks as fire attacks for now.  Note, however, that the main reason I'm hesitant about it is that there's a good chunk of feats that key off of fire attacks, and being able to switch all of your attacks to one element may end up being too strong.  Also, note that enemies here are going to be intelligent, and if they see one person in the group using nothing but fire-based attacks, they're going to prepare accordingly.