So I heard a nasty rumor that CDJ2000's won't work in HID mode with traktor over a usb hub, and that they need to be plugged in directly.

Does anyone know if this is true or not?

What about the sound card in the DJM 900 nexus? I know it's never a good idea to run a sound card through a hub, but would it work?
What kind of difference in latency would you end up with?