I only ever upset a bike with luggage with my bmw that had a massive topbox and I filled that with tools and a gearbox, even then, only a bit upset by the weight, given careless cluch controll and too many revs, I did lift the front wheel a few times negotiating the notorious Spaghetti junction. My 550 k3 had loads of weight that far aft when me and a mate did a weeks tour of Scotland when I first passed my test. Rock steady all the way.