I know McRaven is a proponent for the lower hewing position....and I suspect he has hewn alot of wood! Sobon's books cover the elevated position. Having done both I would never go back to hewing at a lower position.
Keep in mind when we talk of tradition that the logs they had hewn were so large that they were hitting the log at waste height.
http://www.amazon.com/Lumber-Kings-Shant...5612&sr=1-1As the cover in this book shows.