Your right about the USB for G2, didn't Classic and or Deluxe come with a 15 pin connector, serial, something?
A quote from when G2 came out:
NEW INTERLINK (TM) CONTROLLER FEATURES: Now comes with Great Planes New Interlink (TM) Controller with USB hook-up for fast, easy, "Plug and Play" installation. USB Ports are faster in terms of signal recognition.