If I don't. He'll probably find someone else to do it. And he's better off as one of our type, than his previous type. Vampires in his world are pretty sucky. Not as sucky as the ones from this one.
Katherine's going to help him adjust. And, if it goes wrong. We'll deal. I think the Winchester's have a panic room we could lock him in.
But, also I sort of owe him. He kept some secrets for me, when he could have told the entire town. And I did kinda get him hurt on a hunt once.