I have sold just a few of them. One failed after the warranty (1 year) was up, but HotSpring sent me the replacement part - in this case it was the upgraded cell - at no charge. They also sent me a new filter standpipe which was also upgraded to put more of the flow through the cell and keep it from doing what the first one did. I thought that was good customer service. The customer was very happy - I helped him do a water change and get the salt levels set at the same time - and he loves the system.
Other than that, the others have been working fine, and the people report that the water DOES feel softer and have less drying and irritation that they would expect from hot water alone, and certainly less than hot water with high chlorine content.
HTH