Necessary add-on; Wish it comes with a case
While the SR540/800 can roast without the extension chamber, it needs to run on almost full power and high fan speed the entire roast, leaving little room for experimentation and uneven roast. Chances are most home outlets aren't going to provide enough power, but the extension chamber delivers on what it promises to do. Now I can keep fan power on the middle and low power through the roast, allowing the beans with plenty of room to move which leads to even roast.
Because this extension is such a crucial piece, it should have been sold with the Fresh Roast unit. A storage case for the extension chamber would be great as well, but I will have to look for something that accommodates the roaster unit and the extension chamber. These two items are my main complaints that I'm docking a star.