Hugels.. horiz or vertical

I'm looking for info on anyone who has done comparison of using the wood horizontally vs vertically.

Does Sepp talk about this anywhere?

I have tried both ways as an experiment and to tell you the truth I can't tell the difference between putting the wood vertically or horizontally. I think either way is just fine. Sepp is usually putting it horizontally, but I think this has more to do with that it is usually in the form of removed trees and so horizontal placement is much easier to handle and less work. I have never heard him specifically address placing the logs horizontally vs vertically.