Funny you say that..
My buddy started selling their systems, so I told him he could come give us his "in home demonstration" crap so he could get $50. Well, after promising that my dishes would be spotless (as well as anything else), I thought that this may be the answer. I was, at the time, bartering my detail water from a medical supply company and it was a bit of a hassle. SO - $5K later, we had a whole house softener/air purification system and some spotted dishes and car. After going to their office and pissing and moaning, they took 2 grand off and gave us years worth of laundry/dishwasher/hand/shower/car soaps. They also gave us craploads of fake armor all/furniture polish/stainless steel cleaner/window, well, you get it.
So, after wasting your time reading this, the bottom line is, other than water that feels, well, soft, RAINSOFT SUCKS. All it does is replace certain chemicals in your water with salt, which is a spotty substance...and any softener can do that, regardless of what Florence Henderson says.
Spot free can only be made 3 ways - Distillation/Reverse Osmosis/Deionization.