DO the testing with full stock deflection applied as this would be the only time the Assist would ever over drive the control surface anyways. If you max out your servo travels, hold full stick and the move the model in a way that it would try to apply even more input in the full stick direction is the way to test it. Heading hold mode may also be even more aggressive in this way.
Let us know what you find. For myself, since Jeti specifically says that this is it's purpose in the Assist manual I just set the limits in the Assist and forget about it.