Sorry to quote such an old post, but this theory irks me. There's no such thing as coolant "flowing too fast through the radiator" because fast flowing coolant is also spending less time in the engine getting hot. It's a two way street basically, you can't have one without the other.
But anyway... this is such an awesome build! I love the drive train choice and the color choice too!
The problem is cavitation, and it's completely dependent on the engine and vehicle in question.
The cooling system is pressurized, and as the coolant flows the resistance to the flow created by the water pump is what makes the pressure. The thermostat is a point of restriction, but not the only point.
Cavitation happens when coolant under pressure passes the last restriction before the water pump. If the pressure in the system is low enough, the coolant can boil and the water pump cavitates, which means coolant doesn't flow again for a few seconds until the coolant (hopefully) returns to liquid form.
It happens on some cars, and not on others when you remove the thermostat. Your best bet for removing the thermostat on any car is to remove the center of the thermostat and leave the outer ring.