Does this also hold when using drivers like the ones built by Trinamic? A servo is essentially a feedback control loop, ensuring your motor will slow down if is reaching its torque limit. As I understood the data sheet for the Trinamic controllers, they can measure various parameters (e.g. back EMF, applied current,...). Cooperating with the motion controller, a similar feedback loop can be implemented. (Thinking about this, a servo would need to "talk" to the motion controller as well anyway - if the motion is lagging behind due to a torque limit, the motion controller needs to compensate for that instead of just scheduling motion on an independent axis).