I think the actual numbers will be quite low..
Furthermore, I doubt that the PC drives that have reportedlyfailed have done so while exceeding their designed shock limits.
B.sides.. there are very simple cheap things you can do to your PC HD mount that will make it every bit (if not more) resistant to shock related failure.
When venturing out on your own in this field... remember:
1) Heat disipation --THEN--
2) Shock isolation.