Folks have come to this forum to question the design characteristic.... The smokers they purchased would not flow air/heat/smoke properly.... One of our members, boykjo, traveled to one of the purchasers home to modify the smoker and rebuild it so it would work... It was quite a job.....
From what I have seen, the builder did not use and formulae or calculations to design the "convection" system necessary for a "gravity" system to work....
They look nice... He may have done something to improve his design.... But, until it was proven to me the changes were in making an efficient and working smoker, I would steer clear....
Most folks do not know, nor have used a properly designed and properly functioning smoker to know what to look for and how they should function....
Many people were taken advantage of, buy the seller of those smokers.... I have seen them for sale in Washington State on Craig's list.... On E-Bay.... An old adage.... If the price seems too good to be true, it probably is....
There have been folks on here in the last year that swear they are a great smoker and he has redesigned them.... Well... They look pretty close to the same to me.... and, if you have never operated a well designed smoker, how would you know....
Just trying to save you some money....
There are great designed smokers on this site that many folks will attest to.... and how to design them.... dig through the threads and put something together for someone to build for you.... I will be here to help as well as many others....
Dave