I even gritted my teeth, got SCSIFormat from Aminet and did a complete wipe including the option to clear the defect table... no difference, still showing up as 16.0GB.
This may be a long shot, but being a reasonably modern HD, it may have the so-called 'SMART' system, automatically mapping bad blocks and preventing them from being used. Maybe the missing space is due to the large amount of bad blocks?
Typically, used SCSI drives are often scavenged from old servers, which means they've had a busy life, and might not live for too much longer.
-Paul
