It depends on your drivetrain. Roelof drives 8th scale, which has a one-way on the front axle. In 10th scale there typically is a diff or spool in the front axle, which makes a difference here.
On a 10th scale, overdrive will give more steering off-power, entering a turn, and less steering on-power, exiting a turn. Underdrive will do the opposite.
When having a front diff or spool, overdrive and underdrive will always make your drivetrain inefficient. A front oneway solves this for underdrive, but makes you loose braking on the front wheels.
Shepherd V10 Pro 2015 - Matrix tires - Novarossi Engines - Runnertime