There was a test in a Swedish magazine where they compared the 800GS and the Ten to find who they want to go into the wild with. The Tenere won. I made a post about it here:

http://www.xt660.com/showpost.php?p=61997&postcount=1

Also want to add about the weight: A friend of mine bought a brand new 800GS and put it on the scale. BMW lies about the dry weight of the 800GS, it is actually 20kg's more then they say.