I am the one on the Ténéré.
my expierience in deep Sand is more like drisschoufa described with his GS. Pip was able to ride on the dunes with his Xchallenge, but not me.
I have to say, that I'm not that good sand-rider, maybe one with good sand riding skills could do this, but the bike is heavy in comparison to the XC or KTM 690 (~50kg).
As tire i used the Heidenau K69 / K74. I dont think you can get a better tire for deep sand/mud for the Tenere. On the road these tires are ... well very "interesting". Dry and warm its ok, wet and cold like hell
Since the rear rim has a width of 2,75", i was not able to put on a rim lock and can't reduce the pressure for deep sand
You can do a lot with the Tenere when the ground is harder. There it works very well for it's wheight. But my experience in deep sand is, that it's hard work to get through. Maybe with better riding skills, a "not so bendy fork" (I will change to WP48) and rim locks it's better. Steering damper could also help, but I don't have experience with these.