My best answer is........................um,,,,,,,,,,,,,,,,,,,,,,yeah,,,,,,,,,,,,,,,,,,,,um, it all works.
Ok my thought is this, If you use dual stacks, the heat may not spread evenly across the cooker, depending on the style (offset vs RF). It does look cool to have duals, but I dont see the benefit.
I can go either way on grate height exhaust. I agree that it should pull the heat right on top of the grate and help the cooking process, but I dont like it taking up space inside my cooker. I know you could come out the end of the cooker, but I have enough problem not hurting myself without having a hot pipe so convenient to grab a hold of. Just my.02.