Pictures will help for sure. Rule of thumb is to use the shortest servo arm that will give you the deflection you need. As you reduce the % on dual rate you reduce your resolution. Most of us would not notice this until you get below 50%. If your main focus is 3D then it's not really a big beal as the lost resolution is not a major deal just as long as you are getting plenty of power to your control surface. What you have now is a 1:1 ratio. Never go longer on the servo arm then that.