I absolutely LOVE the VSBi door (from Foy's) and have two of them which work perfectly. When I moved and had a garage transmogrified into a coop, Foy's was out of the VSBi and I needed an auto door fast... So I bought a different style(since I do have electrical power in the garage coop).
I wish I hasd waited. I really, really wish I had waited.
I've had one of the Foy's units for well over a year, and it was a used one I bought from a BYCer who didn't need it any more. It has never failed, the batteries have lasted over a year, and the light sensor has needed NO adjustment. The second unit worked just as well.
I wish I had not bought the third one, the different brand. I may take it out and see if I can make one of the VSBi units fit in that space somehow...