RTO uses all available brake pressure and maintains the additional capabilities of the auto brake system with their advantages.
Overriding the auto brake will allow you to put more than the available pressure onto the braes but you will loose the additional safety functions integrated within the system.
Due to the loss of the additional safety features, it is recommended NOT to override unless required, in other words, let the RTO function do its job, it's what it's designed for after all and your performance calculation is based upon that capability. Sometimes overriding is not a better option..., even if it enables additional pressure to be applied.