I have used a phEP and one other kind of Ph pen made by Jenco. The PhEP I had worked well, until I broke the electrode being stupid. The Jenco also worked great, until one of the buttons stopped working
One problem I see with pH controllers in industry (cooling water towers) is they do not keep their calibration, and these are far higher quality than even the top line hobby equipment. I don't know if the saltwater enviroment is less harsh than the industrial one, but I'd be very skeptical that they can keep their calibration.
I never really thought about getting a pH controller personally. My philosophy in reefkeeping is to build the system with intrinsic controls (lower bioload, refugium, aragonite sands) rather than add complicated equipment that will need constant tweaking.