I still bear the psychological scars from doing this in 2010, on ice-covered roads. I believe I may have been the slowest rider on the day, partly due to wiping out spectacularly on one icy descent, ripping a chunk out of my winter jacket and colouring in large parts of my back and shoulder. I walked every downhill after that.
I had a job interview at 7.30 the next morning and muddled through it dosed up to the eyeball with painkillers. I don't recall a thing from it but I must have been more coherent than I felt as I got the job!
It's a cracking, challenging route, but I think I'll save it for the summer (especially as it now has a mandatory helmet requirement).