Wow, here is the loaded question of the day.
I sell and manufacture a lot of these systems for several companies.
I also do regular training seminars for dealers all over the country.
I will answer your question with this story.
A recent training seminar with 50 large dealers on the West Coast. I finished my seminar with "Green Technologies" focusing on this type of system. My final two questions of the seminar were as follows.
"How many of you in this training seminar beleive in this technology and sell it?" Every hand went up with enthhusiasm.
"How many of you have this technology in your own house?" Crickets....
Do I beleive it works, sort of. It works very well sometimes. Many times, it is completely inneffective. It makes great sense to pre-treat small commercial RO's with this technology instead of traditional softening since the salt consumption will greatly exceed the cost of membrane replacements. It is also a good option for areas where softeenrs are not allowed. It is the only real option. I also know that if people claim the technology doesnt work, they get threatning letters from certain people in this industry, the standard "cease and desist" garbage.
We do not offer any warranty, guarantee, etc with this product, that is part of the reason why the equipment is so expensive. The high rate of returns has to built into the price. I never get a call from people saying their softener does not perform as promised. With this equipment, it is a constant issue. I train extensively on the fact that it is not a softener, nor does it replace a softener. It does not reduce soap or chemical usage in a house. I also train our dealers to sell Rain-X, Lemi-shine, and a few other items to help these systems be more accepted by their customers. It is easier to clean yor showers and counter tops with rain-x every few weeks than to haul 50 pound bags of salt around. Add some Lemi-Shine to the dishwasher as well, again, easier than 50 pound bags of salt.
Now, upflow GAC... not a big fan of GAC systems without a backwash valve. Upflow causes poor contact with the media, downflow without a backwash valve ensures low flow in the near future.
If I were in the field would I sell these? Yes, but... I would avoid them like the plague. A true softener with a pre carbon tank (never mix resin and GAC, that is another topic...) will give you far better water quality than these systems ever will. It is hard to ignore the great marketing that is used, I have to write this garbage myself all the time for dealers, but is just that. Marketing.