My JB3's PRIMARY JOB, is sitting on the gas tank of my motorcycle (actually the reason I bought it, recording was an afterthought). It's been running fine, and hasn't picked up any bad sectors (that I know of), in over 2 years. Most of the laptop style smaller hard disks were designed with excessive vibrations in mind, and are a little more tolerant of being jiggled around.
The microdrives however, don't seem to be as tolerant. Lot of complaints on the photo boards of SDDDS (sudden disc drive death syndrome) and when they go, they're usually gone for good.
Minidiscs use removable magnetic media, and the transpost mechanisms really aren't much better then a floppy disk, or zip drive when you come down to it.
If the JB3 can handle road trips on the Harley (vibration city), then loud concerts shouldn't present too much of a problem.
Hope this makes sense...
Rick