[ It's true that he hasn't seen the Slayer's full potential and the two predecessors that he took out weren't up to Buffy's standards either. Maybe he's overly confident, but on the other hand Dawn hasn't seen what he has. If he doesn't have a chance to keep up with Rose, chances are Buffy doesn't either. ]
No fantasy. Not that I'm interested in putting it to the test... not without good cause, at least.