Looks great! Not sure why though, is it big enough to add/remove food from the lower grate? I guess for chix pieces or ABT's or something it would work great, and I guess it wouldn't let all the heat out of the dome.
Does it seal properly? Sorry for all the questions, I'm just dubious of "Mods for mods sake", but this one does look like it could be a valuable addition as long as it doesn't compromise the temperature control.