Etudiant,
I've tried it in the 777 simulator.
With autopilot/autothrottle off, vertically, the a/c describes a phugoid motion, but not very pronounced. Laterally, with the 777's bank angle protection it doesn't exceed 30 degs.
But it needs to be tried in a real a/c as the sim is not 100% accurate. So over to Boeing for that!