Time Pilot,

Sergeant's formula is the one to use to relocate weights on either side of the "scale" and maintain the CG location.

Frankly, I'm not sure what Jim was stating, but I don't suggest you try to calculate the moment of inertia- just doing the things we've discussed will give you the qualitative results mentioned. Just for fun, here are some basic equations on the subject of rotational motion.

moment = control surface force * its distance from cg
OR whatever external forces * whatever relevant distance

mass moment of inertia = SUM (mass of each distinct weight * its distance from cg ^2)

angular acceleration = moment / mass moment of inertia


So, you can see through the formulas the effect of slowing down the responsiveness of the plane by spreading weights out toward the end points. Of course, you can apply this in each of the plane's axes.