I am curious if your angle of incidence on the tail is the same as the other planes. You might be running out of elevator power first. I only flew in the factory demonstrator once but I remember the slats out on final. Air speeds could vary from plane to plane due to installation and instrument errors but I would guess those slats are going to extend at the same angle of attack from plane to plane. Vortex gens on the underside of the tail might be the difference too.
Fred