This side conversation was split off of this topic.
Mario P, I was in your shoes last year, so here is what I found in research, over my first year, and what my PB told me about SWG.
SWG is not maintenance free. You will end up having to add muriatic acid to your pool to fight the PH in the pool. SWG turns your pool basic, so the acid brings it back neutral. Not a big deal, but just a different type of maintenance.
The SWG has a cell in it that will need to be replaced, and they are not super cheap. Cell might last 1 year, might last 3, might last 5 or more. But it is a cost that definitely will need to be spent at some point in your future.
The salt in your pool will cause more corrosion to things that if it were not there. People are correct that it is 1/10 ocean water, but that doesn't mean it is not salty. If you have a lot of plants around the pool, the salt an be a bit of an issue as your kids drip and splash around the pool. Of course, plants hate chlorine as well, so salt or not, this is an issue.
I ultimately went without SWG. I just add bleach to the pool to keep chrlorine up, and when I am going to be away for travel, I will throw a couple of pucks into the Rainbow unit to keep it good when I cant maintain it. It has been my opinion here that people give you the opinion that one chlorine puck will ruin your pool. While their heart is in the right place, and the fact that pucks equal higher CYA, and higher CYA equals problems, an occasional puck wont kill your pool. All you have to do is keep an eye on your CYA via testing, and dont let it get out of control. Now if you only use pucks, CYA will get out of control and cause you problems.