I'm also looking into some kind of water ionizer to replace my current water filter at home. A friend of mine is working in a company selling water ionizer from http://www.long-life.com.tw/ . She said she received a lot of good feedback from customers. Seems it's similar to the Korean one you mentioned.
I think there's scientific backing for it as we know its easier for us to get sick if our body is acidic. So drinking alkaline water may help on this aspect.