Whether or not it’s the worth the cost is certainly subjective but I’m here to tell you IT WORKS! My driveway sees full sun from rise to set so there’s that. Plus my well water is hard as hell (75 tds I just measured). Now add the fact my car is black and you feel my pain.
Just used this baby for the first time yesterday in full sun of course and it was magical. I did use it for full wash (many just do for final rinse) as I wanted to test it out fully. The water behaved so differently it was like it wouldn’t sit still on the paint (note I am ceramic coated) and washed off soap easily. I watched carefully as it began drying fast in some areas and there was absolutely zero water spots. Again, water going in was 75 tds but coming out was 0 tds.
There are several different manufacturers and models out there and after extensive research I chose this one over the rest:
https://spotfreefinish.com/store/DI-Pro-50D-p105868875