I don't rewind yarn if it's in a skein or a ball. Only if it's in a hank. And I have never managed to unwind a hank without tangling it.
Actually, I would probably wind up paying loads of money for a swift, manage to tangle the yarn while I was winding it, and get mad and never use it again.
I actually don't really like center pull balls all that much, and I don't mind hand winding balls, so I'll just hope for a swift.