Any weight reduction in the drivetrain is a good thing. That's just one of the many reasons for choosing light wheels.
I have lightened cranks, flywheels, clutches, rods, pistons, and drive pulleys of all kinds in search of better acceleration. Keep in mind, there is no power gain, just less inertia, so you'll get to top speed more quickly than if the parts are heavier. Some engine parts should never be lightened by amateurs, but flywheels are pretty safe and provide excellent bang for the buck.