FCeng84
Regarding my post about the pitch response, I have been thinking that there were two problems. This situation only occurred when we were held high, and way above the ideal Vnav profile. FLCH was selected, and a grab made for the speedbrakes.
Problem one was minor, and avoidable. There was a rapid pitch down reaction to speedbrake deployment, which of course could have been avoided with a less heavy-handed approach.
Problem two was, I think, more of an issue. The aircraft would pitch down, but the autopilot seemed to have no selected speed input. That is, the aircraft would pitch down and ignore the selected speed in FLCH. It would bust the barber's pole quite happily - I wondered just how far the A/P would allow the airspeed to increase. On the occasions I experienced this phenomenon I had the impression that the A/P had lost the plot, and we would have ended up beyond Vmo/Mmo before the computer woke up. I hope that's not the case, but we had to disengage the A/P in FLCH in order to regain control of the speed.
On reflection, that is not strictly to do with speedbrake pitch response, but more with a remarkably sluggish response from the A/P.
I must say that this was all a few years ago, but of the types I flew in my career it was the the 777 I trusted least, on autopilot.