Rob,
I am glad to see you are researching the topic. Lefty is consistent in other books also, likeFly Fishing for Bass:Smallmouths, Largemouths, and the Exotics. Let the hook shank hang 30 deg or so below the surface.
Brad Miller has another theory. Let the shank be at the surface and parallel to the surface.
Now we have to decide whom we go with. I lean to the Lefty on this one. At the age of 21, Lefty caught his first Smallmouth on a fly in 1947 and has been fly fishing for them ever since. Was Brad even a twinkle in his father's eyes in 1947? Were his parents even dating?
Both angles will catch fish to be sure. Since I do not have all the time in the world to work this out myself, I will go with Lefty.
PS The design of Clouser's EZ Pop kind of agres with this. Then again, Clouser advocates glitter. UUGH!