CR are not hard to understand, I admit they do look formidable, but once that wears off its childs play. If your local or if you wanna swing by I can, as anyone else here on MR, show you the ropes
Im big on dual stage units as they help bring the pH back up before it goes back in the tank, letting u melt the media in the 1st chamber w/o worries and more efficiently.
That said, I bought an MRC CR2 due to there great customer service and great build quality and relatively low price compared to these 1 stage deltecs $$$
They are pretty straight forward as well w/o unnecessary bells and whistles (such as secondary bubble counters and internal pH monitor sockets)
I have ARM media and Zeo Mg granules, this keep my tank at 1400Mg, 430Ca, 8.5 Alk, Sr 10 and for my water volume I have a high Ca/Alk/Mg load. I couldnt keep up w/ kalk/vinegar solution everyday w/o shooting off my PH
you test your tank before and start out slow ( the amount of c02 (bubbles) and the drip rate) once u get it (usually just look for alk to stay stable) its set, as you add more stonies and clams you adjust accordingly.
Trust me Im paranoid about everything that goes in my tank, especially anything that can "kill" it, (anything can really), since its gone in I have not even thought twice about it