I agree totally with Carl. They are just another tool in pool maintenance. I have the infamous Hayward CL-200 and it sits idle for probably 99% of the time but it's there when I need it. I use pucks to raise CYA when necessary and just recently I timed things so I needed to do that and let the pool take care of itself for 5 days. Came back from a mini-vacation to a very nicely balanced pool and all a friend had to do was vacuum when his family wanted to use it. As with any equipment, not just pool equipment, you have to understand it and use appropriately and carefully.
Al