IMHO, the stack script is merely a different implementation of Frederiko’s work with a focus on tagging and more configurable (I hope). The utility script “stacklink” is probably a poor man and DT-only interpretation of Hook. I’m sure that Hook is way more powerful for those who need the capability (e.g. cross-application implementation).
Many people mentioned graphically implementation of links and perhaps two-way links in DT. I honestly have no opinion on that topic.