I had ERS through my insurance company (allstate). Had a flat on my rig and needed help. They had a terrible time finding someone. They eventually found someone over a hundred miles away. This was half way between Orlando and Titusville, FL. I got the impression they were not really set up to handle anything but cars.
My experience says: You will never, NEVER, stop working on it and spending more and more money on it and in the end you can't give it away. Really think about it carefully.
Unless you are very mechanically inclined AND you like to work on these things as a hobby, run away as fast as you can. On top of the mechanical issues, I would be worried about how it handles on the highway, and what kind of storage it offers.
good luck with your decision!