I was under the impression that coolant doesn't have any additional cooling properties over water. Coolant and Water would technically cool the car down equally. The advantage coolant has is it protects the radiator and cooling paths from rust, corrision, as well as preventing the liquid from freezing up in cold temperatures.

I've never heard of changing coolant to be the solution for an overheating car. I understand that long life coolant is suggested to be changed every 5yrs/50000 miles but it wont lead to overheating directly.