Heat transfer fins help if you have a powerful enough oven, for example in a Combi-oven, or a professional convection oven.
Just out of curiosity, how fast can a pizza suck heat out of an aluminum "stone?" Ignoring issues of practicality, would putting heat xfer fins on the underside help, or does the preheated "stone" already contain enough heat at ~550F to achieve the desired results? Nathan/MC-people, did you monitor the temperature of your metal "stone" during baking?
In a home oven you are limited by the heating capacity (wattage) of the oven. Most ovens just don't have enough wattage for this to work. So what you do in effect is take a long time to build up heat in the metal plate, then release it during a short cooking time.