I've worked with the USBHDFSD driver sources before, and I cannot see how it can support disks >2TB.
It seems like it has a bug that prevents it from accessing disks >1.0 TB properly, since it was reported that my IEEE1394/SBP-2 disk driver cannot access disks >1TB properly.
That driver was based on USBHDFSD, hence any problems in the driver might have been inherited from USBHDFSD.
If anyone has the time and means to test, look for:
1. The usage of signed 32-bit variables.
2. Buggy code (E.g. code in uLaunchELF that files off the top-most bit, hence screwing up support for disks >1TB).
3. The usage of calculations and variables that might overflow once disks >1TB are involved.
SCPH-10000 S. MINOKAMO v1.01 (Defunct)
SCPH-10000 S. KISARAZU v1.00 (faulty)
SCPH-15000 S. KOHDA (With warranty seal!) :D
DESR-5100 S. EMCS