After some experimentation, I ended up doing pizza on a stone that sits atop a steel on my gas grill, with another stone suspended above to reflect heat back down. I find that the steel’s conductivity keeps the stone nice and hot while reducing thermal loss when I place the dough, while the stone provides “softer” more even heat to the pizza to prevent scorching.
Does the steel under the stone actually do anything? I think of the advantage of steel as getting things to equilibrium faster, but your stone should already be at equilibrium.
I have noticed a different versus not having it. I think the additional thermal mass helps maintain high, even heat when you lay the dough down, so you get a crispier crust.
The extra thermal mass I would definitely believe, yes! I just wouldn't expect there to be additional benefit from the high conductivity of it being steel.
