... not the other way around.
There are so many tools out there. I think you should give yourself license to pick one that is easier to setup. The Setup Guides are a great way to get started on a tool using a setup you know works for GTD. That way you can concentrate more on learning the methodology than learning and setting up the tool.
Just a suggestion in case it is relevant. I know that helped me immensely finally get started with my GTD implementation.