I am not a reviewer but I did have the Theorem for one day and sent it back. My reasons are that the beauty of the Duo is how it folds. The Theorem completely stunts the movement. It is bulky and heavy too. IF you just want to use your Duo in just a book mode and never fold it all the way back then sure, this might work for you. But you definitely cannot fold it all the way back with the Theorem as the sticky holds the phone in place and all that case gets in the way. Hope that helps. Also, I completely forgot to mention that I called Otterbox and asked if the slim pen fits in the elastic and they said yes...NO it doesn't, it took me 20 minutes to get the pen back out. I guess it is for another pen, but not mine.
