Just replaced the Metz for TKC80's. Metz are indeed terrible for offroad, especially sand and mud; Metz for onroad and light offroad is perfect.
The only change is they make more noise, steering is changed (get used to it) and backwheel is slippery when accelerate.
Put around 1,7 bar in the front for both off-onroad.
http://nl.youtube.com/watch?v=DHe79gT2LJI
Hill climb - it's an easy job:
http://nl.youtube.com/watch?v=ZKlQGvgctz4
Indeed, it's better to have an extra pair of SM wheels
And, you don't want to have a tail mod like me
Greetings from Holland,
Marcel