I bought a RKL after watching BRS's vid on using one in place of a heater controller and basic light timers. Made sense to me... I'd never had a controller before, but it seemed worth a try.
Last November, about six months in, my RKL had been expanded by adding another PB4, and I was using it for several things I'd never really considered before. Then... it wigged out. Equipment quit turning on and off on schedule... it left my heater stuck 'on'... communication between the base and the 2 PB4's would fail for no apparent reason. No support, email was being returned as undeliverable, no phone numbers anywhere on the website... Noting.
I bought an Apex Classic, and sold the RKL. Cheap. To a LFS that _knew_ it had been screwing up.
The Apex is most certainly not any more difficult to use than the RKL was. It's much more advanced, capable of a great deal that the RKL was not capable of... but, you don't have to use that stuff. Instead of plugging in a USB cable, you have to get it on your network, point your browser at it, but as long as you can do that, it's not terribly much different from setting up the RKL, at least not until you start wanting to use some of the more advanced features.
So far, my Apex Classic has been rock solid, and I'm doing far more with it than the RKL was capable of, even when it worked.
Price? RKL was what, $129, right? That's with 4 outlets. Add a PB4, that's another hundred bucks. Add a pH probe, you've added another hundred. Add the rather questionable 'net' module and an SL1 so you can hook up a float switch or two, and you're approaching the price of the Apex Classic, which already has all of that stuff, and is capable of so much more.
I do believe that there's room in the market for an under $200 low end Apex... perhaps a new revision of the Apex Jr. Built in wireless, pH and Temp probes, and a single EB4. Probably sell like hotcakes. Maybe once they get the Trident released

You listening, Neptune?