I haven't tried yet but an additional 22 grate fits above the pizza pan?
yes. it gets hotter there though (obviously)
my ONLY complaint with the stacker is the lack of a bowl/pan.
The included heat diffuser works very well, but it doesn't contain all of the grease like a typical water pan would.
In fact, it will hold just enough grease to be a fire hazard. If you're cooking multiple butts, be careful. (i've only had this happen once, so maybe it was just a perfect storm)