Regarding the First Need Purifier, it looks interesting. However, I must admit that I don't know what "Mechanical Chemical Removal" is or whether that's a fancy way of saying "Activated Carbon Chemical Removal".
As for the idea of the First Need Purifier as a long term water purification, at only 125 gallons per filter the whole system seems pricey.
_________________________
"Learn survival skills when your life doesn't depend on it."