I have a Saito 120 and the battery all the way back in the tail. The recommended C.G. is WAY too conservative.

I also did most of the mods mentioned above. Even with the reinforcements, mine came in at 8.75 lb ready to fly. It's a great kit.

I'm confused by the torsional stiffness question. With D tube sheeting and shear webs, these wings are pretty stiff.