It's only too late for a change if the aircraft returns to kit form first.
I am in the process of building a new stabilator with the pivot at 25% chord and actuating it from the forward splicing tube, located at the leading edge.
Before I read your response, I hooked everything up and tried to move the leading edge up and down with my finger. It had some movement and my mind imagined it clattering up and down at flying speed. Not good!
The original plans and article (RCM 1977) did not state any problems with flutter, but I suspect it didn't attain much in flying speed since it was powered by two glow .15's. Mine will be powered by two 2915-5T-8Y Tower Pro brushless motors swinging 3 bladed 9-7 props.
A friend of mine pointed out the construction article of Keith Sparks MD-80 in Flying Models (Nov. 06) and he has the pivot point of the stabilator at about 5% with the swept wing design.
Thanks for your help.

Bob