Results for second test (one more badblock run still going):

/dev/sdd is 400GB Hitachi Deskstar in a SteelVine 2000
(Sil 3726), connected to external SATA connector on Sil 3124

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debian:~# time badblocks -w -t random /dev/sdb > badblocks.sdb.txt

real    287m48.162s
user    11m49.856s
sys     4m14.692s
debian:~# cat badblocks.sdb.txt
debian:~# fdisk -l /dev/sdb

Disk /dev/sdb: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table
debian:~#
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