RE: 1.20 Edge Review, the beginnings
1.25" if you want 3D throws, 1" are better for precision. And it depends how far you set the clevices ont he horns form the surfaces too...
Be careful about the Hitec blue arms - sometimes the splines are not very tight. I prefer the the Hitec Karbonite arms over the Hitec aluminum ones. The MLP aluminum ones are best - but they are not strictly necessary for a plane this size. I used MLP 1" arms all around set up for precision flying (low rates.)