The progression from the trail bikes of my youth to a built machine from Munich is one that spans decades. The GS is a very competent dual purpose machine, but if you want to swing the balance toward off-road, the laws of physics begin to assert themselves. The XR650L from Honda cemented that fact, but I saw an X-Challenge for sale and it spoke to me as aesthetically-challenged BMWs sometimes do. This model was only in the US for a year and did not do well, so it is relatively rare here.
However, it is a true dual sport with more HP, more Torque, and the same weight as the Honda. On the road, it is a revelation in comparison. It is also fuel injected, and has slightly better ergos. What it does lack is any significant after-market support !