Ca reactor

I like toys so I have a lifereef lcr2 on the way. Ups has been kinda derelict because it shipped on the 29th and still is in another state. Anyway I have been looking at regulators and whatnot. I have seen a lot of recommendations for the carbon doser. Chiefly because it claims not to dump co2 when the tank gets low. Now I have been looking at the $100 Milwaukee regulators. If i am using my apex as the backup to kill the co2 flow when the ph gets too low then what's the added benefit of the carbon doser? I mean other than costing 3 times as much.
This will be my first go with a ca reactor. My intentions are to tune it and run it primarily off the needle valve and use the apex as the safeguard.
Input?