I've been using aquacontrollers for nearly 10 years, and they have been working great for me. The software is not the greatest, and connectlivity to a PC is via a serial port, but it controls my heater, cooling fan, main tank light (with length of daylight changing as seasons change), sump light, moonlight (with dimming and time of day changing automatically), main return pump (turns off and on for feeding), and my powerhead (on during the day, off at night). I orignally used X10 modules with my first Aquacontroller, and now have an AC jr using the DC8. I monitor PH, but do not use it to trigger any actions, although it could if you were using Kalk or similar.
I haven't used the RKE, but I have heard it is pretty nice, has better software, and uses USB connectivity to talk to the PC.