I use an Apex and my system is completely automated. The only thing my apex isnt managing is my automated water changes which is done using a litermeter III and a second Litermeter add on pump. My Apex acts as the failsafe for that and will shut it down in the event of my salinity being too high, water on the floor, sump too high etc.
My apex handles my top off using redundant float switches. That too will shut down in the event of salinity levels that are too low, water on the floor, sump too full etc. I also use solenoids as part of my failsafes.
I am on the road about 60 days out of the year and not only does the Apex give me piece of mind by letting me check my system where ever and when ever I want but it also provides email and text notification in the event of an issue. Its also simplified my life by eliminating much of the manual labor that goes along with having a 550+ gallon system.
The automation aspect has made my tank more stable and healthier than it ever has been and truth be told, I dont think I would want to have a large system without a good controller.
As far as the reliability, my Apex is about a year old right now. I have 5 EB8's on it along with 2 PM1's, a PM2, 2 Lunar Sims, break out box, PH, ORP and conductivity probes and it has not skipped a beat. I have had absolutely no issues with it at all.