I've used a foil pan (to hold water), and I have also foiled a pizza stone. Both do a good job of acting as a diffuser. Easy clean up with the foiled pizza stone. Water pan isn't too bad, just have to dump the water somewhere.
I've used a pizza pan once, only thing I didn't like was the pan held the drippings, since it has a raised edge. The drippings even with aluminum foil somehow baked on.
Char-Griller Akorn , Maverick ET-732 , Red Thermapen Backlit