By the way, for the Gigabeat F40:
OF lsusb MTP mode: Bus 001 Device 022: ID 0930:0009 Toshiba Corp. Gigabeat F/X (HDD audio player)
OF lsusb MSC mode: Bus 001 Device 023: ID 0930:0009 Toshiba Corp. Gigabeat F/X (HDD audio player)
Rockbox lsusb: Bus 001 Device 024: ID 0930:0009 Toshiba Corp. Gigabeat F/X (HDD audio player)
So, the Gigabeat does not appear to use a unique ID number for the two modes.
By the way, for the Gigabeat F40:
OF lsusb MTP mode:
Bus 001 Device 022: ID 0930:0009 Toshiba Corp. Gigabeat F/X (HDD audio player)
OF lsusb MSC mode:
Bus 001 Device 023: ID 0930:0009 Toshiba Corp. Gigabeat F/X (HDD audio player)
Rockbox lsusb:
Bus 001 Device 024: ID 0930:0009 Toshiba Corp. Gigabeat F/X (HDD audio player)
So, the Gigabeat does not appear to use a unique ID number for the two modes.