What are the disadvantages of a twin boom aircraft?
The main disadvantage is flutter. The booms add a mass behind the axis of elasticity which will twist the wing when it bends. This twisting will increase the local angle of attack when the wing bends upwards and increases the bending moment, and vice versa on downward deflection. Once the plane flies fast enough, flutter is hard to avoid. The main remedy is to make the inner wing stiffer in bending and torsion, so the flutter frequency is shifted outside of the flight envelope. This costs weight, though.