I support the notion of the black hole spell not providing any Juice, just as a concept, since it would also give more utility to the "Telekinesis" spell as applied to controlling enemy movement. (With the black hole being predominantly offensive and Telekinesis being mostly practical/support, with the latter making it easier to get Juice while the former makes it more difficult/impossible.) The fact that it also affects performance provides a non-balance incentive to change this as well.
Oh, and that jukebox glitch seems pretty obscure - does it work on any other weapons?