Stefan

Not sure if this is of any help but have you heard of or tried USB over IP: http://usbip.sourceforge.net/

here's a guide for doing it with ubuntu: http://www.howtoforge.com/how-to-set-up-a-usb-over-ip-server-and-client-with...

Could the x2go-server or x2go-client machine be configured to use this to solve your thin-client usb mounting problem?

Brian