I recently installed a 10c for a friend, and during my initial test, I adjusted the lens "roll" to get the image oriented correctly. I believe that the lack of any calibration made adjustment more difficult. I would suggest adding a scale, such as +/- degrees, to make setup a little easier. Plus, calibration would make it easier to return the lens to the correct setting in case the lens is accidentally moved. Along those lines, a mechanism to lock the setting in place would be helpful.
Calibration for lens rotation on 10c