There's a lot of misinformation and misunderstanding of heat transfer in the hotrod circles, and anyone who says/believes that Evans cools better than water has been misinformed because it's just plain wrong.
Here's the simplified heat transfer equation:
Q = 500*GPM*deltaT*Cp
Q is the amount of heat energy in BTU/Hr that we can move from the engine to the radiator.
GPM is the flow rate of the coolant from the engine to the radiator in gallons per minute.
DeltaT is the temperature differential between the top & bottom tanks
Cp is the coefficient of specific heat for the coolant being used. It's a physical characteristic of the fluid itself and is an indication of how much heat that fluid can carry.
Water has a Cp of 1.0 and all other commonly available coolants have a Cp that is some fraction of 1.0. What this means is all commonly available coolants will carry less heat away from the engine than water.
Pure (100%) Ethylene Glycol has a Cp as low as 0.55 to as high as 0.69. When mixed 50/50 with water, the EG/Water coolant then has a Cp of from 0.79 to 0.85, so all other things being equal, it will carry from 20% to 15% less heat away from an engine than pure water.
Evans coolant has a Cp as low as 0.64 to as high as 0.68, so all other things being equal, it will carry from 36% to 32% less heat from the engine than pure water.
What does all this mean?
Pure water is the best coolant available. 50/50 water & EG is the most common mix used, and works nearly as well as water. Some people who go with a 50/50 mix and a bottle or two of Water Wetter see no difference after adding the WW. Others who go with pure water and a bottle or two of WW see a nice drop in engine temperature and give WW all the credit, but based on the above relationships, It's easy to see the WW had little to do with the temperature drop and it's the pure water that has everything to do with it.
Those who run Evans will have scary high engine operating temperatures. Increases of 75-100 degrees F are not uncommon, and in fact, to partially offset its poorer heat transfer abilities, Evans recommends smaller pulleys be run on the water pumps so more coolant is pumped.
Here are Evans' positive attributes:
Will not freeze or boil over
Little or no danger of cooling system corrosion when changed over from EG correctly
The negatives:
Extremely high engine operating temperatures - this may or may not be a problem for you, but for myself, the much higher operating temperatures are enough to keep me from ever using the stuff. The engine manufacturers are familiar with an operating envelope from 180-220 degrees F and know very well how reliable the engine and its ancillaries will be within this envelope. Once that envelope is raised 75-100 degrees, we're in unknown territory.
If you feel your engine can tolerate the higher operating temperatures, give it a try, but don't do it because you've been led to believe it will cool your engine better than EG & water, or pure water. It's simply not true.