I recently made an arm using the VEX. I started with direct drive from the motor, but the arm would not support much weight be for the motor failed and was not able to hold its position. I then moved up to the chain and sprocket set, I used a gear ratio of 16:1(motor turns 16 times for every turn of the final gear). Under load the chain broke, I knew this was a possibility and so was not too disappointed.
This did get me thinking, under load what is the maximum gear ratio where the motor will fail before the chain fails? This would be useful information that could keep some one from breaking the chain.
I could test this my self, but at the cost of several chain links. Is this a question your engineers have an answer for, or would be willing to test?