Controllers are nice and all, but I dont trust them to run my tank. I have had a reef tank for over 10yrs, and have never had a controller. I believe in true failsafes, each able to stand on its own, without interacting with something else. For example, I have my heaters on a Ranco, my top off on an osmolator, my CO2 reactor is on its own power, with a Milaukee controller, and all critical circulation pumps are on different circuits. My main pump is even on a dedicated, stand alone circuit. Only a whole house outage or pump failure will kill the main circulation. And even then, there is enough other circulation that the system will survive for several days.
If one of those systems fails, it is highly unlikely to take down the entire system. The tank can go without a reactor, or individual pump, or top off water for several days without much harm. However, with a controller, should that 1 piece of hardware fail, your entire system could be in jeopardy. If you dont think it can fail, just take a quick look at the Neptune forum, its top of line equipment, and they fail everyday. The probes are notorious for going out, and causing havoc if you have them control lights and chillers, and various other things dependant on temp. IMO, its just bad practice to put
something as expensive and delicate as a full reef system on a single point of failure like that.
Now, with all that said, I did recently purchase an APEX lite. The cost was a bit to swallow, but I am going all out on my new tank, and I am lucky enough to have the budget to do it right now because of some bonus money at work. Otherwise, I would not have purchased it.
The only thing I will have the controller actually control, is my automatic water change system, and all the lights in the system: Frag tank, QT tank, main light, moon light,fuge ligths etc. Other than that, I am not controlling anything, but simply monitoring the tank. I travel a lot, so it will be an added bonus to be able to monitor PH, temp, and possibly even a webcam from the apex. Although the controller will have the data from the probes, nothing will be acted upon with that data, its strictly to monitor.