I've done it once and though I love riding that area, that will probably do it for me. Glad I did it, though. I may do Three Gap sometime. It took me over 10 hours and that's just too long for me.
http://www.bikeforums.net/fifty-plus...l#post14809097

I agree with jppe that Hogpen is the only really difficult climb and the descent of Hogpen is not fun at all. Too many long straight sections where you worry about getting too fast for the eventual next turn or worry about overheating your rims and blowing off your tires from all the braking. Might be a good place for road discs.