"They run the grill taped up most of the time anyway so obviously cooling isn't an issue. Besides, as previously mentioned, the temp is controlled by the thermostat. It doesn't matter how much heat the rad dissipates, the thermostat will maintain its preset temp"

yes but if a BLACK rad cooled better the coolant would be say 230 instead of 235-240. Once the t-stat is open it's open until temps drop under the designed temp. My car has a 160* t-stat in it but the temp will go higher. ....just saying.