That's fascinating!
I know the one section of Pine Flat that's 21 - 22% for about 1/2 mile was too much for me. I had to put my foot down and ended up walking a bit. (I was also still sick and started wheezing, and I really didn't want to start hyperventillating there!)
In the Giro, the riders will do a section of road - unpaved - that goes to 24%!! Amazing!! Should be a great spectacle.