The weight increase with the stacked frames is insignificant at worst. About the only thing to account for the increase in weight is the little ali spacers and blocks and a few extra bolts. That'll never kill the model's performance. With the proper paddles and a healthy motor like the new TT 39, the model will 3D as well as anything out there, and you'll never have to be concerned with overstressing the airframe. Spin the head at 1900 or so and let'r rip. It's damn near impossible to wear this model out.

Ben Minor