You know, Kyuubi-mode naruto was fast enough to get in close to Neji even though he was using the Kaiten, and Naruto only tried to stop it with Brute force, ie he made contact with Neji and then the Kaiten knocked them away because Neji couldn't start it fast enough. So if the user of Chidori has speed equal to or greater then Naruto's when he's using his Kyuubi Chakra, it seems to me that their would be a similar effect, except that instead of both getting knocked away, the user of Kaiten would have a hole in him as he got knocked away. Especially if it's someone like Kakashi, who is most likely much faster then Sasuke, Lee, or Naruto. But then again, if it's Neji's Uncle, then maybe he can start the Kaiten faster. *shrugs*