Do you or your engineers have any thoughts or comments on these shafts' resistance to breaking—especially as a result of micro-cracks? Do you use special “toughened” resins to reduce this concern? We did some flex testing and the shafts seem very strong, but we want to feel confident that they are unlikely to fail as a result of being dropped, for example. Any feedback you can provide would be much appreciated. We are pleased with the product.