Hmmm... Interesting.
I've been using Neilsen style kalkwasser reactors for 5 years, nary a problem, and they're incredibly cheap. I've maintained Calcium and Alkalinity this way, despite having a somewhat heavy coral load. They also take care of top-off, something you will not achieve w/ a Caclium Reactor.
Both systems have their plusses and minuses, but take what you read w/ a grain of salt.
I'd be happy to answer any questions you have about them.
- Mac