If you're doing any serious work around the tech tree, the tool will likely come in very useful because you can work on a visual diagram rather than trying to do it all in text files, etc.
If you have cash, I recommend buying a pro license - the editor has far better functionality, for example you can select a technology and then show all successors (everything that requires that tech) or predecessors (everything you need to get that tech). You'll need the free Flying Logic 'Reader' (works on Windows, Linux, Mac OS X) to view the files.