I have the JBJ auto-top off system and it works great. I set up a 25 gallon rubbermaid container as a reservoir for RO.
Yesterday, I set up a mechanical float switch for the reservoir. The main reason I did this was to handle the situation where I forget to turn off the RO water. It seems to work fine. However, the obvious thought is that I could just leave the RO on all the time, controlled by the float switch. Then, the system is completely automated (auto-auto-top off).
Of course, the problem is that I am plumbed to an infinite source of water. If the reservoir float switch fails, then I can pump a ton of water. However, this is essentially the same thing we all have in our toilet tank, and no one worries about those failing. If they failed, it would have the same problem.
Anyone here running auto-auto-topoff? Any predictions of doom?