I am impressed so far (other than the increase in electric bills). The D1 is set to clean for one hour a day (which uses a lot of juice), and it stays crystal clear with a table spoon of choline after each use. I shock evey 2 weeks and water change every 4 months. (this website is great, btw)
This is the most maintence free spa I have ever owned.
Once the chemicals are balanced at startup, a tablespoon a day is all I ever need. I did not pay for the expensive Vison system, and I now test my chemicals about once every 7 days. I am assuming the ozonator must be the trick.
My last spa used bromine, and I played hell with itching and chemical balance. Just my 2 cents.