Also, a lot of the issues with the less expensive dosers are user error more than the doser, like having it siphon all your ALK into you tank when you should have check valves on both ends (the container and the line to your tank).
Even the Neptune DOS can get stuck on. No gadget is we have is immune to failure. Take dosers for instance, I can replace my CoralBox every year if I wanted to do so because of the price point. I did my research and see that it has been a fairly reliable little dosing pump so I took the chance on it. I could have bought a GHL or Neptune DOS, but I liked what I saw with the CoralBox for the price point.
With that said, I will get something that will monitor my parameters for my frag tank soon so I can have my Apex shut off the outlet if things don't look like I want them. Even the Apex has its own set of issues to deal with.
At the end of it all, the only way to not be concerned is to not have any electronics in our systems, but that is a far-fetched idea (just my $0.02).