Didn't do any two up on my own 650GS but, went away with a mate who was riding one (Dakar) whilst my wife and I were on an Africa Twin. In every respect, other than the seat, the AT was better for two up travel with luggage. The motor on the AT was smoother and had more power which meant a more relaxed ride required less gear changes. Once we'd dumped all the gear, tent, cooking stuff, clothing etc, the difference was alot closer though. I suppose it would depend on how light you travel.