Does This Debunk the "Coolant Can Flow Through the Radiator Too Fast" Idea???

IMHO, from what I've read, it sounds like everyone is right to some extent.

The lower the flow rate, the more efficient the thermal transfer. This does not mean higher flow rates do not provide any additional cooling by pushing more through in a given period of time. There is a point where increasing the flow rate is completely offset by the efficiency loss, but there is little chance of finding it. Cavitation would be a problem first. Adding gpm is like adding rows to the radiator or running an engine driven or electric fan. It isn't as efficient as a one row and moving at 45+ mph, but it still helps.

Reduced flow rate (such as underdrive pulleys) reduces the parasitic loss which can be ok when the engine doesn't produce much more or anymore power than stock and the cooling system is adequate at low speed and pump rpm.