I haven't seen a system that requires you to hold the button, just press it and forget it. The original systems were due to children being ran over and maimed or killed by the blades. That system would kill the engine when placed in reverse with the blades engaged. The new system allows you to back up with the blades engaged, but you as the operator is required to manual manipulate the system to bypass the system. that way when somebody backs over their child, the mower manufacturer can say in court that the operator made a conscious decision to bypass the system, and by his own hand due to negligence killed their child.