I've been dosing the DIY one for over a year and a half now and it's keeping my tank's parameters very stable. But before you do start dosing it get all your parameters to the level you like first.
Also one thing to note is that this thing is always "out of stock" everywhere. That's why I'm going to switch to a calcium reactor.
While down at RAP I went to top shelf aquatics and the first thing I notice is 1000ml bottles of the stuff right when I walk through the door. I grabbed 2. Should be good for a long time.