I can really only go by my own experience. My own Reef Fanatic solenoid continues to require a light "tapping" to get it to click on. I took it to Kevin at All About Fish and he told me that a lot of people bring him Reef Fanatic solenoids. He recommended milwaukee.
I am talking about the solenoid only though. The rest of the regulator (inc. the needle valve) haven't given me a problem.
jdeveaux: I haven't had a calcium reactor for long so I don't know too much but I always thought that bubble count wasn't so important in a pH-controlled system. That is to say, whether you have 10 bubbles-per-second or 30 bubbles-per-second, the solenoid opens for a set "high" pH and stays open until until a set "low" pH. In your experience, to what degree does bubble count precision matter?
I have to say that the AquariumPlants unit looks good though simply as a high-quality alternative to a solenoid. From what I have been reading, solenoids fail all over the place left and right.