The double pumper has the ability to give a massive pump shot in all four venturies as all four open in light throttle situations, which is great for big cams and heads with low port velocity and "city" type rpms. Great for getting a car out of the hole quickly, but lousy on fuel mileage.

In a steady state cruising situations, both could be tuned for equal fuel economy. Steady state is not what you're dealing with in around town. The dinky high velocity primaries are what is what makes the thermoquad inherently better and delivering fuel economy around town.

Likewise, both are capable of being absolute turds if they aren't tuned properly.