Great thread! I'm very interested in building a double-chamber oven like this as well.
I'm curious though, does anybody know how the wood consumption and heat retention compares to a traditional cob oven?
Does the heat escaping from the chimney mean that this uses more wood to to reach sufficient temps for baking and then looses heat more quickly?
Or does the heat retained by the cob and higher initial temperatures from the more efficient burn negate whatever heat is lost through the chimney?