I have one. Good flow rate and no waste water, but ineffective as a PO4 remover and product water yielded a high TDS. All this thing is a carbon block, a stack of Poly Filters and a basket which you can put a PO4 remover in. But as all of us know, Poly Filters are helpful at reducing PO4, but not great and there aren't any PO4 resins out there which can bring PO4 levels of tap water down to 0 with only 1 pass.(they send you Kent Phosphate Sponge with the unit which does nothing to help with PO4)
The filters DO NOT last as long as they advertise.
If you were going to do this, I would highly suggest pre-filtering the unit. Place a couple of micron cartridges before the unit. Then after the unit, I would do a DI cartridge. When I ran it that way, I was changing the micron cartridges monthly and the DI resin every 2 months. This helped the unit's filters last longer and did a better job at dropping my PO4 levels. The problem was adding a DI cartridge slows your water production.
Not worth the price IMO/IME