In my old steamplane, the B707, full elevator travel was equivalent to around four units of stab trim so the stab could easily overpower the elevators. There were about 12 units of stab trim available.
On the earlier models full elevator travel could load up the stab trim drive so much it stalled so you could end up in a situation whereby if the stab ran away you would run out of elevator to counteract it.
Do the FBW aircraft have a separate stab trim mechanism or is it all handled by the autoflight system?
Regards,
BH.