The grades themselves are only 6-7%, but long and seemingly unending. You'll see signs on the downhill side often going "you're not down yet, still 4 miles of 6% grade" ... just don't let speed get away from you, and if you are ever in doubt, slow down another 10mph. Better to have people honking at you than you honking at people to get out of the way because your brakes are on fire!
But as long as you respect the grades, it shouldn't be bad at all.
The Green Machine -- 2000 Mountain High Coachworks Summit (Spartan chassis / Cummins ISC)
...and F-Troop: Fearghus, Fiona, and Frankie (Cairn Terriers)