I bought a LaCiE drive last year and from what I gathered most external USB drives are preformatted as FAT32. I'd recommend using FAT32 if there's any chance you'll do something like dragging it over to a friend who is using Windows.
I keep mine plugged in at home all the time. I've noticed rarely (once every few months), I'll try to use Amarok or Kaffeine, but it can't find the file. If I open up the drive in some sort of file manager, it's enough of a kick in the pants that Amarok realizes that the drive is actually connected.
Transfers tend to be slow. I came across this post by accident a while ago (which I haven't really investigated yet):
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'I had the odd Linux version mount external FAT32-drives (USB sticks) with some crappy mount parameters that it would have been quicker to write the data on the HD with my own hands - yes, literally.
So if you happen to use Linux..
Try mounting the external FAT drive without the "sync" option, i.e. with
"mount -o async".
But you'll have to remember to umount the external device manually before removing it; sometimes a lot of the writing happens only delayed at the time of umounting - at least it did sometimes with my SuSEs.'