Does the Air Vent belt-drive whole-house fan offer a better wattage to CFM ratio than the direct-drive whole-house fan?

The belt-drive whole house fan offers an advantage over the direct-drive from the standpoint of efficiency and noise generation.

The belt-drive offers an advantage over the direct-drive from the standpoint of efficiency and noise generation. How much more efficient? It has to do with being able to tune the belt/wheel ratio to the motor performance. The noise reduction is due to the fan vibrations not being transmitted directly into the motor and thus through the frame but only from the fan through the frame (one component removed from the vibration chain).