I'm also not aware of a PCII for our bike. I think you are thinking of the PCIII with the Serial Cable vs USB. The only difference I'm aware of, and I'm not even 100% sure about this, is the level of fuel adjustment is greater on the USB version. The serial version allows for adjustment at 500 rpm increments whereas the USB version allows for 250 rpm adjustments. Also the USB version allows for tuning of each cylinder, I'm not sure if the serial version has this ability or not.
Brian