The unpaved sections are more gravel than dirt. Try riding on a gravel road at 90mph. I don't like it.
Jack Wilson used to say " Dirt is for worms and taters, asphalt is for racing"
I wouldn't either, that's why I would rather be a spectater rather than a rider.
Have to say though that I'm very impressed with riders who do that. With all due respect, isn't that the reason Eddie Mulder has won the vintage class of Pike's Peak so many times when it was mostly gravel he being a great flattracker back in the day...?
P.S. I enjoyed this interview with a young looking Eddie Mulder (can't believe that he's 66 years old!) http://www.blip.tv/file/1634338