[GTOLou]

Most people will tell you that light-weight flywheels are miserable on the street. A heavier flywheel give you more rotational inertia and is less likely to cause your motor to stall or require higher reving when starting from a stop. Light-weight flywheels are at there best with track cars that are at constant high rpms and need to accerate faster out of the turn etc. They are not meant to be driven in stop-and-go driving.

To a lesser degree I would think a light balancer vs. heavy would do the same. Jim Hand has a section in his book about balancers.