I resisted owning a controller for a long time. Why? I'm an industrial automation software engineer. I do that kind of thing for a living... never really wanted it as part of my hobby, too.
While researching a heater controller for my new tank, I watched BRS's review of the RLK as a heater controller/light timer. What the heck. Bought a RKL. Over the next few months, as I figured out what it could do, I expanded to a 2nd PB4. After about 6 months, the thing started messing up. It'd loose communications between modules, ignore my timers, even left my heater stuck ON once (no damage, luckily).
I went to their website... no support phone number. Email sent to the published support email was returned as undeliverable. Repeated attempts to join their support forums went unanswered. If they offered any sort of reasonable support, I'd probably still be a happy Reefkeeper customer. They didn't.
I bought an Apex (classic).
That was several months ago. So far, so good, no troubles. I've expanded to a 2nd EB8, added a DIY breakout box, and increased my reliance on the controller to handle more and more automation. At this point, my Apex does the following:
Separate timers for blue, white, refugeum, and under tank cabinet lighting
Heater controller
Skimmer - over high level sensor in the sump turns it off, stays off for 10 minutes following a power outage or reboot.
ATO reservoir refill system, based on a high and low level sensor in reservoir + backup timer + water leak sensor
Powerhead timers
Water change logic that shuts down return pump, powerheads, ATO, dosing system, reactor pump and white light during a water change
Dosing pump (Kalk, ESV Calc+Alc) shuts off if pH varies outside window, or if sump high level sensor is tripped
Mixing station manually started refill system, opens RO/DI solenoid for 3 hours, starts mixing pump, continues running water until high level sensor is reached. Timer (and mechanical float valve) safeties in place.
Manually REMOTELY start/stop water change refill pump as needed from tankside
Email alerts if temp, pH, heartbeat alarms triggered, or if ATO reservoir refill or mixing station refill cycles take abnormally long
It's a helpful tool, that enables me to spend more time enjoying my reef, and less time messing with it. I'll never own a tank without one again.