How are you able to improve payload and performance using reduced power?
Very very badly worded to the point of being wrong on my part
and since you rightly picked me up on I'll offer the following but you probably know this already.
Say I need to lift XXX tones..If I use some reduced thrust and normal climb I'll lift off Y metres down the runway...if I plan to lift off at Y plus a bit down the runway and use improved climb to meet the performance criteria I can perhaps carry the same payload and use a larger reduction in power ( power by the hour costs, etc now coming into play) ...or carry a bigger payload with the same power reduction.., or something between the two, or really haul the post with full power and improved climb ...etc etc...... (and if you'll excuse me I'll stop digging now).
Whatever the physics as a result you very much do end up further down the runway at rotate (and a bigger V1/Vr split) than in days of yore. On our Triple Operation we didn't used to see a V1/Vr split very often.....nowadays, except, at very light weights, it quite common to see a 10 knot or more split due to the higher Vr..
I've probably fouled up the above explanation but I certainly second the comment made previously that the bean counters love improved climb and other gems such as aft C of G for payload/engine cost reasons..but it can remove some of the "fat" we were used to seeing out of the window..