If you use the highest bit rate on mp3 or wma, then unless you have a high-end audio system, you will probably not notice any difference, the down side is that the file size becomes considerably larger.
Also editing of a wave file is a lot easier then having to deal with compression at the same time.
Regarding USB, since it was introduced there have been 3 different speeds over the years.
1. USB1 1.5Mbits per second.
2. USB 1.1 12Mbits per second
3. USB 2 480Mbits per second
Its main competitor however, called Firewire/ IEE1394/ Ilink has also increased in speed, from its original 400Mbits per second to 800Mbits per second.
Probably the reason Yamaha did not fit USB 2 is because USB 2 did not really become a standard computer motherboard fitment until the P4 came out in about 2002, were as taking in to account the 137Gb hard disk limit, and PC133 memory that is used in the Tyros 2, this would indicate that it uses the old P3 technology, which only went up to USB 1.1.
However old technology or not, it is still a dam good board.

Bill