I know the owner. I had him do some work on my offset. Here's my personal opinion as I have seen these upfront.
They are a backwoods clone. He uses excellent insulation but the construction is thin metal. Little bit thicker than normal sheet. I think the insulation definitely help with this. The new ones might be different as I was only looking at the prototype.
Chief cook for P B & j's BBQ Team/Dubbed "Skippy" By the legendary Mike Davis