I am considering buying either an SI2 or an SI3. I am new to smoking and have done a lot of research and this smoker appears to be one of if not the best line on the market. I had been considering a Bradley but am concerned about what users have to say about them and the quality sounds much cheaper than one of the SI models. I can't find the difference between the 2 and 3 anywhere on the site any info would be appreciated. Thanks