High niftiness coefficient there, but you have to wonder about how it affects cab structural integrity on unibody designs, how well the door seals against wind noise, and how the door fares on side impact crashes. I am sure for the money, there are a lot of other mods that you would rather have.
The major problem I see for us in winter weather areas would be snow and ice build up on the exterior, and what happens to that when the door retracts. Otherwise, it seems to be more a souther cali or Florida area item. But cool as hell!