Intruder, all performance factors are satisfied with the takeoff thrust flex obtained from the takeoff performance application . Noise is also reduced. At 1000feet AGL, when climb thrust is selected, improved climb also reduces noise. When an aircraft that can take off at 575t on some trips, but only need 420t on shorter trips, huge takeoff thrust reductions are available.
Obviously this won't work for those little regional jets like 777 etc.