I've been thinking about this a bit lately, and after finding this most recent article thought I would open up a dialogue.
I know Marco, who I hugely respect, is a firm believer that a Neapolitan oven cannot be perfectly replicated without traditional Neapolitan materials. I've also read similar comments from Steffano Ferrara, and I know he ships materials from Naples for all builds and in the article I am about to posts even jokes he would bring the water if he could.
All that taken into account there does seem to be some contradiction. In the following translated article Ferrara says he no longer uses the traditional bricks and instead uses fire bricks with much better results:http://www.dissapore.com/cucina/stefano-ferrara-si-fa-presto-a-dire-forno/
I've also read about a transition from an older style floor to a newer style harder fired floor. Again probably very similar to modern materials used in other areas of the world. In another article I read recently Gino Sorbillo stated that Ferrera will not let anyone see the process of putting sand and salt about the dome. I agree with this statement because I've never found documentation of what goes under the floor or above the dome and vent. The key here is sand and salt. This is sounds like thermal mass not insulation and goes hand in hand with claims the ovens are extremely hot on the outside.
I think this rambling mess is basically getting to the point. We all know these ovens produce great pizza, world class. Do you feel the traditional materials are a benefit or a handicap? I'd particularly love to hear Craig's take on his Acunto and Mathews take on his commercial oven.