Richard, you are certainly correct in your belief that the best unit is a mechanical fan. I spoke with Griffin and two other aluminum radiator manufacturers regarding the best setup to cool a Chev motor at low vehicle speeds. Everyone (100%) suggested a mechanical fan with a tight fitting shroud with no leaks at the shroud/radiator interface. I did what they said and can idle for hours in 110 F weather here in Tucson.

Electric fans are an example of specmanship. I spec my fan to flow 1126.6 cfm and you top me with 1126.7......and someone believes me. Electric fans work using three things: motor rpm,
fan diameter, and blade efficiency (design). You cant jack the speed up because of (1) cost and (2) blade tip speed. You cant get too big because of mounting issues. And you cant spend too much money designing a perfect airfoil because you already paid for the damn mold......so you cheat on advertising. Why do they put a $1.50 motor on a $100 fan? Because they ran out of $1.25 motors!