I hate to tell you this, but there were some old PC outlining programs that could do much of what you want, including the ability for bits of an outline to appear in multiple places. This was not a popular or easy-to-use feature. I understand you want what you want, but you don't really know that a lot of people would find the set of features you advocate useful. I think most people who stick with GTD end up trying to make their systems as simple and robust as possible.
Originally Posted by Folke