Roger, depending on the speed, I would say yes. At lower speed and in extreme situations like In a stop and go on a warm summer day you notice that the aluminium radiator has more capacity than the smaller OEM plastic one. The temperature keeps cooler for a longer time and the electric fan is still rarer used than it is anyway the case with the 4/4. (I never changed to aluminium because I felt the need due to coolant issues, it was just a precaution action not to wait until the OEM plastic item blows off).
At higher speeds over an extended and even distance, e.g. 140 km/h in 5th gear, for more than 10 minutes on the same piece of road the car gets warmer than with the smaller OEM radiator also now in the winter time. The assumptions why this could be so are discussed above in the thread.
