I read somewhere that it helps with drivability, when you shift from second to third next time, take a little longer to releace the clutch, you will notice that the rpm's will drop, then level out then drop. Suposedly(sp) it makes for smoother shifts.
Now think about stop and go driving, could the same thing apply??
About the flywheel. If we got an even lighter flywheel, not only would it rev up faster, but wouldnt it rev down (whatever it is called) faster as well, without all that cyntrifical force / weight spinning. That is of course if the engiine is not crontrolling it in some assenine aspect. But my l/w flywheel sure sucked in stop and go, had to feather the clutch alot more to keep it form stalling.