Is a 54 reg 650 GS powerful enough to go two up touring with full luggage around the mountain passes of the Alps and the like? I have an 1150 and my son goes on the back of me and my wife has the 650. Our daughter is now old enough to go on the back of her and I'm a bit worried it'll be a bit gutless when it comes to some big hills. Can someone with a bit of experience with a 650 GS put my mind at rest or should we be thinking of changing it for something with a bit more oomph?