I guess you're right.
The LBE does put out a good amount of heat but when you look at the amount of mushrooms that were on that pizza, which was only 11", I was still surprised it came out that way. Especially when the baking time was around 3 mins.
But I know what you mean. When I used that much mushrooms in my regular home oven, pizzas were always soggy in the middle. The problem lies partially, I think, with cheaper stones. I'm talking about the thin ones you can buy at Target or Bed & Bath. They're less than 1/2 inch thick which is totally inefficient, in my opinion.
Plus, I've read on numerous websites that sell pizza stones, that they'd draw moisture out of the dough. That's not true. The moisture still evaporates from the top.
Do you use a second top stone in your home oven?