I have been using a Treager Little Tex for years. It has worked well. But, I saw the PB series 4, version 2 at Lowes and was impressed by the sheer volume of space and the WIFI capability. I have done two smokes so far and it has been fantastic. I do have a question. Since there is so much vertical space, is there a preferred position if using only one of the shelves? Should it be close to the top, bottom or in between?