after having several regulators (two stage, single stage, ...blah blah blah, I can say the carbon doser is the best. If you can work it into your system, do it. As far as a reactor, I had a Geo624 and it worked flawless. As long as the reactor is sound and has good flow it will serve you well.
In my opinion (and only my opinion), get a carbon doser, a coleparmer Peristaltic pump and monitor how ever you desire. You will have a system that is unbeatable.