Tim,
Sluggish ---- nothing to do with the available performance, and everything to do with reduced/derated thrust takeoffs ---- for as long as I can remember we only use as much power as we have to ---- keeping the top EGTs down does all sorts of good things for turbine life.
I am not entirely unadjacent to a B787 operator, who is very happy with the commercial results, both the 800 and 900 are actually producing fuel burn figures below book and quite a bit below contract guarantee --- a somewhat unusual situation.
The pilots (all B777 pilots) love them.
Tootle pip!!