banktoturn - only in the morasses of my mind. Doh! You are right it is inertias effecting the flutter of the surface, not the location of the mass as I said. The aero horn is a good place to add mass as it will help balance the static loads on the control system.

I was thinking along the lines of an all moving tail with the pivot at 25%. Assume the airplane were pulling positive gs with the mass of the horizontal ahead of the pivot. The aero loads go through the pivot but the mass hanging out in front tends to give a leading edge down moment on the pivot. If there is any slop in the system it will allow the elevator to command more positive gs than you want. The airplane might oscillate about a trim condition as a result but this is definitely not a flutter thing.

Thanks for pointing the flutter thing out. As I mentioned I barely passed dynamics so I wouldn't trust my answers myself!!