That makes a lot of sense. I would ask VMware to consider having the VITK return $null instead of "undefined", as that is consistent with other powershell conventions. But otherwise, now that I know what to expect I can safely document it thusly in my book.
I would appreciate if anybody has some fancy SCSI-3 drives try this out and paste the output.
Author of the upcoming book: Managing VMware Infrastructure with PowerShell
Co-Host, PowerScripting Podcast (http://powerscripting.net)