Glad it worked. In case you need it in the future, the easiest thing is probably to use sudo to copy the user's files:
the permission problem is because HFS+ supports unix style permissions, so when the drive is mounted they are respected by linux. Naturally the UID and GID are different though so that makes them inaccessible unless you sudo or create a custom user with the same UID and GID as the OSX user.
sudo cp -a "/media/Macintosh HD/Users/crashy" /media/backupdisk
you don't see this problem on NTFS disks because the permission scheme is so different that linux just mounts them with permissions disabled.