I've built a Flip3D and I'm wondering, is it better to attach the push rods to the "bottom" hole in the control horn and the outside hole in the control arm on the servo to get large throws? OR??? Get a longer aluminum control arm for the servo (using the outside holes) and use the middle or upper holes in the control horns?
Which way is less likely to pull-out the control horn?
Thanks for any help on this.

Generally speaking it's best to use the outer-most holes (when practical) in all control arms. This provides the most stability, least flex in the control rods, and least chance of flutter.

You'd be better off with a longer servo arm and using the midpoint on your control surface horn. You want to keep as far away from the control surface as you can, while still getting the amount of throw you want. If you are using a computer radio, make sure you go into your dual rates (hi rates) and end points and set them as far as they can go, then limit them mechanically. This will give you the best resolution and least amount of flutter in the system.

Using larger servo arms and moving further out on the control horns minimizes the impact of play in the servo linkages. Longer servo arms are the way to go - stay away from inner holes on the control arms.

-Curt