We used T63's and MT21's on our Trans America off road trip. The T63 rears are an ace DOT tyre and lasted very very well. The front T63 wasn't so good on the road sections but we did 6000 miles of mainly Gravel and dirt roads.
The best combination for us was T63 rear and MT21 front. The MT21 fronts did dish out quickly when we go back on the roads heading for Baja though.
You can't beat the T63 for cost per mile on DOT tyres. Our Tourance's haven't lived up to the reputation as a lasting tyre so fitting Heidenau K60's next week.
Hope that helps. The Baja 1000 was fantastic by the way.