The "ScaleBlaster" is nothing but a "WalletBlaster. All it will do is make your wallet $300 lighter.
If you have hard water--"hard" enough to be a real problem--you need a plain ol' salt-based ion exchange system. For well over 40 years, living here if Florida, "out-in-the-county" as they say, and using well-water, we have hard water. We also have had salt-based softeners for those years, they last 15-20 years or so--or until you decide that old "mechanical timer" inefficient monstrosity needs to go.
That last happened for us three years ago when we replaced an old Autotrol softener with a Pelican system with a flashy electronic control that monitors usage (in gallons) and recharges itself only after 1400 gallons have bee used (this and the amount of salt used per recharge is fully configurable--the old unit recharged every 4 days whether it was needed or not). It was not cheap, but it is the "best there is" with a pretty stainless steel tank and state-of-the-art valving and controls. It has a 20-25 year estimated service life, before the filter media will need to be renewed, We use 8-10 40 lb sags of salt per year, typically $ to $5 per bag at Ace Hardware or Tractor supply (whicheve has them on sale).
The "sodium in the treated water" boogeyman is just fear-mongering. The treated water has ≅7.5 mg of sodium per quart (whole milk has 200 mg/quart; beer has 38; bottled water is the same, typically 5 to 10 mg/quart).