re: GTD Software Advice
What is the successful outcome vision?
What are the necessary steps that contribute toward that outcome?
What is the very next physical action you can take to move toward this outcome?
If you are just getting started with GTD I would recommend looking at your tool-choice less in terms of which tool is the best and more in terms of which tool is the best coach for helping you learn the habits. Paper is as good a tool as any; and the truth is that most veteran GTDers migrate through various tools over time -- sometimes because the tool is no longer supported, costs too much, or just simply because they need a change. So just go into your tool-choice knowing that you are likely to migrate. Perhaps that will make the initial tool-choice a bit easier.
Also really think through those above questions. Your true outcome vision may be peace of mind in trusting your tools than it is finding something that fits X, Y, and Z together and syncs them perfectly. There is a big difference between those two outcomes and a lot of difference in how your time is spent in pursuit of each one; so tread carefully and good luck.