I have always used a 60-40 mix (antifreeze-H2O)Before my waterpump and thermostat change the temp gauge usually hovered at the 'NO' mark. It now sticks right before the 'N'.Both readings were within the 'normal' range and there is heat.
Personally I would rather have it low than high.

stock 95 LX,6cyl ATX 98.5 wheels with Yokohama AVID T4's