[unknwn]

I learned about the difference in throughput between USB2.0 and FireWire rests in the quality (quantity?) of error checking and correction is much higher (more thorough) in FireWire than USB2.0 . I would need to go back to my course notes to nail down the specifics, but, I used this snippet of info to help steer me towards the FireWire interface (FA66) that I chose.

I also remember that during my decision making about the purchase, I found that interfaces that were more portable did not specify USB2.0, only that they were USB. When I investigated further, I learned that a majority of devices marketed as USB were actually only running "Full speed" which is a big difference compared to the theoretical 2.0 specification.

Another determining factor for me was the fact that a device rated 2.0 WILL default to the slower "full speed" rate if another device in the chain ( mouse/ keyboard/ ect. ) happens to actually only perform at this slower speed.

In other words, if you are going to use these USB2.0 interfaces you need to jack it into a port that is not shared with other supposedly 2.0 spec. devices.
When I say "shared" ports I am referring to ports that are stacked on top of each other, and, any ports that exist in a hub. When you have ports that are integral to the motherboard that are physically above/below each other -or- plugged into a header using the same wire, they will default to a slower speed of whichever device isn't blazing along at the theoretical 2.0 specification.

I have a Belkin hub on one of my computers that is made with uncommon circuitry that judges and steers EACH port on the hub to overcome this little understood aspect of USB. The product is unlike 98% of of the hubs available. It was more expensive, and much harder to find, but impressive in it's abililty to overcome that drawback in USB.