I haven't used any of the flywheels mentioned, and MP is more and more a commercial deal than a gear head one so the info there is suspect.

As you have found out, the amount of imbalance is different. You can adjust the amount of imbalance one of two ways. More eight in the same spot, or the same weight in a different spot. Like a teeter totter, the farther away from center the weight is the more effect it has. It may be that these flywheels you mention have more than one spot to mount the weight?

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.