We have been selling the units since the late 1990's. We don't use them in our work but provide them for clients that want them. We have had little issue with the units over the years, in our experience they have been reliable.
In the few of those situation we have encountered, several of them we mounted the fan on the roof, and had and electrical contractor wire it. Its not pretty, but the client thought it was better than a retro fit on the exterior.