Yes. According to Canon documentation, an external USB hard drive is recognized as "External Media" by the camera/WFT-E4 II A. That means you can use it in several ways: save to the external drive while shooting, record to multiple destinations simultaneously, or use the camera’s Image Copy function to copy images from the CF card to the external drive afterward. So the unit supports both workflows you described: direct recording during capture and post-shoot backup from the card to the hard drive, without needing a netbook.