I have been thinking about doing the SM100 on my full rigid singlespeed, 32x18 or even 32x16. Finishing the race is my only target (well, maybe not too far behind Denis is another). But the Death March and the HAIRY descents would probably destroy me mentally and physically. The sweeping truck might find me laying trailside weeping and gnashing of teeth.
I have a geared and full-suspension bike, but I'd rather not to bring that 30+ lb beast to a long ride. The other two are both full rigid SS. I have a steel hardtail frame on the garage wall that can be build up with gears and a front fork. However it's always fun to eye on a new bike - especially when there is a legitimate excuse :)
So here is a preliminary list of choices - all XC full suspension and should be perfect for the SM100:
Specialized S-Works Epic
Santa Cruz Blur XC
Titus Racer X