srnet:
Ah, you did not mention before that you were using a 'shield' with the UNO.You will get the best and most helpful answers to your questions if you provide a description of the project and the hardware you are actually using.
Sorry you are right, the shield is a motor driver using a independent power supply. The project boils down to a motor arm with a large degree of freedom and hopefully scalability. This makes those two wires I could be saving a huge winning in end if I could use a multi-core with just the D+ and D- running up to the arduino's.
I was hoping to know if that was feasible or I should give up trying.