I like to ride Gruber from time to time. But on my R² (WR250R) a lot more than my big fat Pig (KLR). Stillwater 500 is a good spot too. Its not so bad for the Pig. My friend, Krabill, rides it on his KLR.
Have you been down to Clayton (near Talihina)? Its a real hoot! Great dualsport spot.