I dunno, my bro's Cougar seems pretty accurate to me and that's USB

In fact, they claim they went with pots over optics because pots had a much highter accuracy.
Which is probably true until you start using them for a bit, and find you have to take them apart to clear the carbon dust out...
Someone made a kit for it that replaces the pots with magnets and Hall probes 'tho...
Nothing really wrong with USB 'tho, aside from the fact it doesn't work in DOS so I couldn't play, say TIE Fighter, with a USB stick...
And if the HID accuracy was too low, you could always make your own hardware and driver interface using one of those microcontroller boards...