I live in Arizona where the water is hard as a rock! I tried the PC and went back to SC. What I did not know is that swapping the two can cause a chemical reaction in the hot water heater. I was having brown water come out of the hot water heater and the plumber asked if I had swapped the two at some time. I said yes and he said that was the reason the hot water heater was failing. If you stick with one and do not swap you are safe.
Bottom line, if you can afford the PC then you are ok.