What is the advantage of a "stepped" flywheel?

[RoasT BeeF]

Just wondering what the advantage/disadvantage is. Pro's/con's of stepped vs. flat.

 

[92awddsm]

I believe the stepped flywheel on the dsm was made so they would have more area to add weight. The stepped flywheels only came on the turbo models. This leads me to belive they needed a heavier version to help the takeoff in the turbo dsm for consumer comfort. The evo has always had a flat flywheel including the usdm evo VIII. And it has always been a performance car so they didnt need the extra drivability comforts.