The idea in a mid engine car is that everything is working against you, especially with a mechanical pump located in the traditional belt driven location. Most of the water volume is below the pump inlet, the length of the system is very long compared to the intended design (front engine/ radiator) and the mechanical pump impeller speed is being varied all through its efficiency curve including the high speed portion where it more than likely cavitates.
Add pressure losses in the system due to turns in the pipe, welds protruding into the tubing, and restrictions directly in line with the flow direction like thermostat's and include air pockets in the mix and you can see why our cars overheat.
So why not design a system that addresses as many of these issues as possible. Place the pump inlet in a position that provides as much inlet suction head as possible, run the impeller at its most efficient speed and regulate flow rate with a variable duty cycle, make the effective length of the system as short as possible, and reduce restriction to as little as possible. Once you have done that the radiator must be able to reject whatever amount of heat you efficiently deliver to it.
Why worry about turns in the piping and other restriction? Because they all increase the effective length of the system and in turn reduce system pressure which reduces the rate of flow in the system. Heat does get transferred where the coolant contacts the tubing wall but turbulence in the pipe delivery system just isn't an efficiency way to do it. Besides most of us have insulated the piping so it's not leaving the system there in any case.
Heat rejection in the radiator is a function of, WATER FLOW VOLUME THROUGH IT, total surface area of the radiator, heat transfer efficiency of the radiator materials and construction design, and airflow speed thought it. What we want is as much water and air flow through the radiator in a given length of time as possible. Airflow volume is a very big deal and here is where a carefully sealed and ducted radiator on both the inlet and outlet are important. We want as much of the coolant heat transfer to take place in the radiator as possible and not transfer the heat into the engine bay and cockpit.
I guess I am saying every little bit helps.