I know these stuff. It's hard to say it works or not. If the water is not too hot, the water circulate like central air system. It works a bit. With it, there is almost no scale or even there is, it is very soft. But if the water is very hot like used in cement factory, it doesn't work at all. I think all the manufacture know this, but just keep their mouth close for business. We see it as nutrition. Well, you never know it works or not.
All the theory just theory, no hard evidence could prove them.