Problem with the Grimsel (and many of the more open Swiss passes) is that it is far to easy to massively exceed the speed limit. A couple years ago, I was trying to catch up with some guy going up from Gletsch, and I was hitting 100MPH with my ST2 between corners (it has MBP heads, and been on a diet. Got to the top and discovered I'd been chasing an R1.Outstanding, that was SO COOL!
We traveled over the Gimselpass after WDW2007, unfortunately we couldn't see much because it was snowing but the is a road bike heaven.
Not only that, if someone on a cross street decides to pull out because they can't see him, oops. But it is quite a lot like street luge, but more freestyle.If there is stopped traffic ahead he is a dead man.