I think that the DHF should be a live document. The reason being that from experience, the original idea of the device is rarely ever the outcome. While it may be useful to have a document of the thought process, it is more useful to have a record of what the device ultimately became, on the production line. The document would most likely be more useful being a live document to keep track of the final decisions. Very rarely will people refer back to documents to check the development process. This is often done with memory, word of mouth, and experience. Referring back to incorrect/outdated documents can cause more confusion than clarification.

-Michelle