Never had any problem using the 777 speedbrakes in flight. Always used them smoothly though. They were much more efficient than those of other types I flew on.
Never felt betrayed by the autopilot neither.
However during sim conversion sessions I used to demonstrate what would happen if the speedbrakes were quickly retracted in a descent close to VMO/MMO. Noisy experience! The reason, I think, is the autopilot is not wired to change its 0.2g vertical acceleration limit unless, perhaps, a substantial enough overspeed has occured.
Last edited by DJ77; 23rd January 2011 at 10:07.