I say rev it all the way past redline and let the gearing do its job, but what do you consider powerband?
Looking at a GTIs dyno graph,
Shifting at 6800rpm brings the rev back to ~4900rpm which has the meat of horsepower but torque dropping pretty soon which make it feel as if there is less pull(not as much torque).
Shifting early at 5500rpm drops the rev back to ~3600rpm which has less horsepower(than @5500rpm), but you are dropped in the meat of the torque.
HP or TQ?...Which makes the car go faster as they usually switch places at about 5200rpm? Debate away.