I had a CR Spotless system years ago. They were very good with support, answering emails, etc...but I just didn't get the completely spotless drying that was reported. We also tested the water and found that the DI water produced by the system was slightly more acidic than the water feeding the system. (A friend has a tropical fish store)
When I got mine, it was the early version that had a light on the output side that would show if the system was still functioning. Later, I upgraded to the one with the TDS meter.
I got tired of changing out the resin, and the cost was up there, too. I used to buy a cardboard drum of the resin from CR Spotless and refill the canisters.
Maybe my expectations were too high, but it just didn't give the spot-free rinse I expected and I wound up going over the car quickly with a towel anyway, especially on difficult to dry cars like the old Viper.
I currently have my car wash hose bib tied to the water treatment equipment in the hose. If I get spots, they easily wipe off. I also use an Air Force Master Blaster from Metro Vac to get most of the water off. A quick wipe with a good towel and some Duragloss Aquawax finishes the job.
A note about leaf blowers. Electrics are OK for blowing off the car...but gas blowers often put the exhaust into the air flow which may get some oil spots, etc on the car.