The pictures didn't come through. The servo torque seems sufficient provided the mechanical advantage is there. Some would advise against nylon gears but I have run them in a 70cc airplane without issues. I would not do so today though. A 1 inch servo arm would be a good length but what is the arm made of? Ball bearing at the end of the rod? I am going to assume you mean ball link. If so ball links are not a good idea on plastic arms. Under load it will allow the arm to twist and that can be your cause of flutter. So far you have not mentioned how long your control horn is. That would be the part of the control system that is secured to the aileron. You will want to measure from the hinge to the point where the pushrod connects. With a 1" servo arm you would want that dimension to be at least 1 1/4", 1 1/2 would be even better.

bottom line is that to avoid flutter is to have servos that you think are a good 20% more power then you need, have good mechanical advantage, use ball links only on metal arms, tight hinge lines and make sure the servos get enough voltage to make their max torque. The latter means all wiring should be 20 ga and minimize connections whenever possible.<br type="_moz" />