I disagree (I think). In this specific instance of an oven and pizza cooking surface (tiles, stone, whatever), the only way the cooking surface can get to higher temperature than the thermostat is by having a good IR absorbtive surface (I find burned spilled sauce and cheese on the stone to be an effective means of increasing IR absorbtivity, but one that can lead to breakage
). The only thing getting over the thermostat temperature is the heating element, and the only way to get that energy to the cooking surface is radiation. The other pathways involve first getting the transfer medium (air) up to the thermostat trip value....
The conductivity of the cooking surface material, once it's up to temperature, is then crucial to getting that energy out of the surface and into the cooking crust. It's also important depending on where the heating element is - depending on if you're trying to get the heat through the stone from the bottom or not. In a top element situation like Canadave is asking about, the pie on top kinda gets in the way!
The capacity determines how much energy has been stored in the cooking surface during preheat and how long it will flow into the pizza.
Although the cooking surface can hold onto the energy better than the air, I don't think that's necessarily good. Once the pizza is on the surface, the conductivity between the pie and cooking surface is the primary thing. (Although that probably involves convection of superheated steam for some of it on the very small scale.) Getting the oven air reheated because most of it went out of the oven is then the secondary concern (or in a top heat situation using the radiation from the top element to directly heat the pie). Balancing the primary and secondary heating gives you the good pie.
Lets see, a 18" square of copper, 3/4" thick, for an experiment........ $777.14 from McMaster Carr. Not including shipping or surface treatment.......... Ow, Ow, Ow.
I think we're mostly trying to voice the same things, but are rushed for time. And "simple" ovens are much more complicated than we normally think.
In any case, the only reasonable (cheap) suggestion I can think of for Dave to try is to get another set of tiles, heat them until dry, cool them, lightly coat them with oil _both_ sides, then "season" them in his oven until they blacken. That will allow them to be better IR absorbers, and should give him a higher temp. Especially if he keeps opening the oven door to spill out the air, causing the element to keep turning on. And keeps them close to the heating element. The tiles will, of course, no longer have an unsealed surface.
How hot something gets has little to do with its ability to absorb IR radiation, or any other form of thermal energy. How hot something gets is directly proportional to its specific heat capacity coupled with its thermal conductivity. Copper can absorb IR radiation better than platinum, but because of it being a better thermal conductor, it cannot get as hot as platinum because it is losing heat almost as fast as it's gaining it. The same goes with capacitance. It doesn't matter that stone can absorb more IR radiation than air. What matters is that it can hold on to that thermal energy better than air.