Desert riding is where some banshees have really shined! Send out one of the Leager protrax, Lone star outlaw, Sundahl, or the twister LT bikes. Many desert riders have moved on the 4 strokes so all the tall seated desert banshees have been parted out long ago. I bet there is someone with a desert bike that could run with it though.
This desert race, does the challenger get to pre run the course?
In all honesty, any one who is a pro level rider and races the desert of of their back yard will definitely decimate the average banshee. But on the hills, dunes, gravel pits, drag races, and flat track TT races, good luck.
Props to your buddy if he is really as good as he says. A lot of my buddies out west are fucking desert rats. Riding the natural terrain has made them friggin stellar riders!