Vessbot's analysis is excellent. The only other thing he should added is that it works fine. I've only ever had one significant failure in several thousand hours on the type. Dont over think it. Runaway Stab. Checklist works fine if you have a problem and all else fails put the little feet of the PFD aircraft symbol on the horizon and set 80% N1 then work the problem. Fly the f@#king aircraft. Not that hard.