If you were going to upgrade, and you weren't limited to those choices, would you go with something else?

The shock rating business is only important to me if it makes any difference to how the drive will hold up with normal use in the dock in the car. I don't know that the quietness of the drive is a huge point for me, but if everything else is comparable I'd go with the quieter, even if a few bucks more. If the difference in operation shock rating is anything more than negligible (and I'm not an expert, so I don't know if it is) than I'd probably go with the 4K80.