Yeh I know what you mean. I no longer walk up a 6/12 truss. Cant believe I use to do that. Haha getting older.
I wait til the sun comes up and dries the roof, and wear sneakers, and still don't like the edges.
I found out that just concentrating on your work takes away any fear of heights one might have.
Then again, when the bucket your working in is swaying in the wind, it does make your butt pucker :-)