I'd never heard of Evans waterless coolant before Lee... but I read much of the information at the link you included. Do you use it? or have friends that use it? *wondering about the user feedback*?
I looked for it online and found it available (full conversion kit for small block chevys) on Amazon for $299, which included 3 gallons of the Prep, and 4 gallons of the coolant.
Most 'user feedback' I found was from racers...