Exactly as Tom said. The oven will work great no matter how you configure the vent at this point, but if you got crazy and crunched some numbers the traditional vent would be the least efficient, followed by the traditional vent with insulation between it and the dome. The most efficient would be a straight up vent with a fully insulated dome, but again we are talking laboratory level stuff here. In practice they will all work great for you. My only caveat is I would put a damper in the flue if you plan to do a traditional vent, otherwise you will be convection cooling the dome once the fire is out as I have laid out in other threads.