Having a cr will definitely make ur reefing hobby easier and lessen your chores. But foolproof or not, will depend on your own tuning. I've known guys who go on long business trips and never had problems with kh issues using a cr, its pretty reliable if u ask me, unless ur digital timer or feed pump screws up. As like anything else when comes to equipment, like a failed return pump, chiller etc.
I believe others may have postive or negative views towards cr based on their own expierence, maybe they can share more input on this matter. My first experience using a cr couple yrs back was a nightmare, could never get it tuned, but that was because i was using a different method from now. This 2nd try at cr with the new method has been only positive by far.