Craig, I can't answer your question directly, but when I'm comparing forum hacks I usually base my decision on the discussion of those hacks. At the vBB hack forum, for example, each hack has its own thread. I look at the feedback and questions that have been posted, and whether the issues seem to have been resolved. Whether the author is still posting can make a difference - it's common for an author to post a hack and then move on to other things as time passes.
To some degree, you can also let the complexity of the hack guide your decision. If you are adding a few lines of code in one program, for example, there's a lot less risk than if you are changing code in many programs and templates. Of course, always be sure you have a good backup of both your programs/templates and forum database before implementing a hack.