Lord Spandex - I was not having a go at you flying a 737.
LeadSled- I will have to disagree with you. Physics would have to dictate that a 380 at FL410 will have more inertia in any moment arm direction, therefore will be harder to accurately hand fly especially after a disturbance.
I know nothing of Boeing checklists- But the Heavy/Super airbus checklists call for the Autopilot to remain connected when in severe turbulence.
In my company- anecdotally, when there have been pilot disconnects of the Autopilot at High cruising altitudes due to overspeed's (twice over the the himalayas), serious Altitude busts occurred.
The message that the training department says - is
"Leave the autopilot in at High Altitude"