I think your list covers most of what is best and worst of the Snape fan's take on Snape. On the matter of Blood prejudice and Snape's turn to the good side. My problem with this is we never hear Snape's voice confirming that he is actually working for Dumbledore and the right. We can surmise that he is, but perhaps he's not. It's this abigouity that fasinates with Snape, It is still very mush is he or is he not?