Hello Everyone, I came across this thread in a google search for the same question, and thought Id share what I learned, to maybe help others out with the same question. (also registered, lots of great info here)
So I also have the Smittybilt 8.2x6.2 awning, and I ordered the ARB Deluxe Awning Room in both the 2000x2500mm (6.56x8.2ft) and the 2500x2500mm (8.20x8.20ft).
The awning room will attach to the smittybilt just fine. It slides into the rail along the back face of the awning mount, and also the front face, and clips to the poles just like it does on the ARB awning.
The dimensions are the issue here.
The 6.56ft x 8.2ft Arb Room does not fit the Smittybuilt I have. Its 6.56ft wide and 8.20ft deep, where as the Smittybilt Awning is 8.2ft wide, and6.2ft deep.
However, the ARB Room in 8.20ft x 8.20ft will fit, but rather loosely. There is quite a bit of slack, but its not "unusable". I have decided to keep it, and just clamp the excess to one of the poles, to take up the slack. I did a youtube vid of the awning attached to my smittybuilt, if anyone would like to see how it fits - I hope that helps answer any questions about how they work together.
Thanks