Installed the 917 HD-S in July 2024, because our city water throws appreciable amounts of scale and organic iron into our plumbing. The water smells, tastes and looks better than before. Can drink from the tap now. Humidifiers have less discoloration at cleaning times.. Skin and gastric irritation is gone. No loss in pressure so far (we use 2 1/2 baths regularly). I think this filter works. It costs a bit more and I'm constantly looking for discounts for the replacement filter.