Anyone wash their coach with a deionized wash system?

Mr. Clean used to sell a car wash system that included a cartridge to remove minerals from the water. It worked great. The cartridge was used on the final rinse, no scale anywhere. It also works excellent on the house windows.

The system was kind of expensive so for that reason never really caught on I guess. When they quite selling them a bunch of cartridges showed up at a local surplus store and I scooped them.