Probably the point of the question relates to Vmcg considerations.
With a derated (but not a reduced thrust - as the rated thrust remains the same) takeoff, the lower rated thrust may result in a lower Vmcg permitting a lower min V1 and reduced ASDR. If the takeoff at a higher rated thrust previously was accel-stop limiting on a modest length runway, the use of a derate might permit an increase in RTOW.
This is an interesting curiosity and periodically comes up in PPRuNe discussions. For larger aircraft at light weights on shorter runways it can make for significant RTOW deltas. If you run a search on Mutt's posts you will find a few examples.
Last edited by john_tullamarine; 19th May 2004 at 01:06.