Thanks for the feedback Jeff, just starting to look at this now. It was very interesting to see the trial event at states, it looks to be a lot of fun.Don't think so. The vein is just an extension of the motor stick to hold the upper rotor. It is fixed to the motor stick and rotor on this design. The lower rotor is held in a bearing and is free to rotate with respect to the stick. I suspect the 'vein' is a separate piece to keep its weight down (no motor torque to deal with) while extending the overall length of the copter for stability. For some reason the builder doesn't want the motor stretched that long.
In flight, the rubber is attached on one end to the lower rotor which is free to rotate in the bearing. On the other end its attached to the motor stick (which is attached to the upper rotor). Note, the motor is twisting on BOTH the lower rotor and the motor stick and upper rotor. When you release the copter, the upper rotor AND stick spin one way and the lower rotor spins the other. Equal and opposite reactions and all at work. About the only thing not spinning in that style copter is the center of the motor, it unwinds from both ends!
Oh, a thought, as a starting point consider using the distribution of weights from those designs as your budget for distributing your heavier weight to maintain a similar balance. Example, one prop weighs .08 gm / .34 gm total weight or . So your props should weigh about 1/4th the total weight budget, or one gram. That leaves around 50% or two grams for the motor stick. this is only a starting point, but probably a good one.
Hope that makes sense. If not, just ask.