My AD F-100 instructions do mention it, it says to drill into the l/e of the stabs and put in lead to balance them both.
Harry, that is what the instructions say but they are incorrectly written. I had someone check with the factory when I built mine and what they actually recommended to us is that you balance them to neutral and then remove 25% of the weight that it takes to fully balance the stabs to neutral.
This is the same process that was recommended by BVM in the manual they produced for Tam's F-18 when they were selling that model. BVM specifically recommended that the stabs should not be fully balanced on the F-18. I don't think Tam ever balances any of his flying stabs when he builds planes.
I don't know the reasoning behind not fully balancing the stabs in models but this is why I have always let mine fall forward a little. I figured they know something I don't I guess...