The difference, and it can be a big difference (to total or not to total a bike from a minor incident) is that on the BMW F800GS they are welded to the sub-frame. In the Tiger, the frame is a one piece... So once it is bent or a weld broken, the whole thing is compromised. Back to the Triumph Tiger, I agree with you, bolted on or welded on, it is a problem because there is no sub-frame. The difference is that when it is bolted on, you can remove them when not carrying a passenger or when going off-road.