Would it be possible to add a monitoring/sniffing interface to either the client or the server so that one can capture the complete traffic
between the host and the device?
(Control-, Bulk-, Interrupt-, Iso-transfers for all endpoints)
Could be helpful for embedded firmware development on small microcontrollers.
Eg.: http://www.fourwalledcubicle.com/LUFA.php (USB host and USB device support for Atmel AVR µCs)