No experience with saltless water softener. However, i do have a recommendation: if you have an unfinished basement, get yourself enough Pex to reach from pre-softener to where the spigots go outside for your hose. 100 feet is under $30, and you'd need a handful of fittings. Cut and cap off the existing lines near the spigots. Then connect the pex to the spigots. No more salt in the garden. No more salt on the vehicles when washing. If the salt killed off plants in your garden, you must have some seriously hard water! But, in the long run, rerunning the plumbing to the outside spigots could save you money, since watering a garden uses so much water, leading to more frequent water softener regeneration. The cost of that salt really starts to add up. Speaking of which, I used to think salt is salt. My wife insisted that we switch to the Morton's rust removal salt. I thought it was simply salt with a different colored bag - and a $3/40 pounds higher cost. I was wrong - there are additives in it that really help remove the iron.
As far as saltless water softeners, it was hard to find a source I trusted.
http://www.consumerreports.org/cro/...-need-to-know-about-water-softeners/index.htm Apparently, a standard by which to test these magnetic softeners is still being developed. Culligan and another distinguished water softener company have both attempted to make magnetic based softeners - and both gave up, because they're not as effective.