Our team decided that counterbalancing was an absolute must. Our arm has a constant-force gas spring to help counteract the weight. Unlike most other springs that exert a force proportional to the distance compressed/extended, our gas spring exerts a constant 225 lbs in every position. A simple sum of moments calculation is done to figure out the distance to mount the spring.
The arm is designed so that one tetra completely balances the arm and unloads the motor (van door). An empty arm means the motor works a little to keep it down and two or more tetras means the motor works to keep it up. We have found this to be highly effective as the motor runs a lot cooler than arm designs in previous years.
You can see it
here.