I don't track tasks in TheBrain. I tried several times, but I have a lot of recurring, date specific tasks, and contex specific tasks. I ended up managing the task list in the plex more than I did doing the actual tasks.
The main things I ran into were: I now use OmniFocus on my Mac, iPhone and iPad since they are always with me and my task list is always available. I use TheBrain for project files, links and references. No way to manually arrange thoughts (important for managing the tasks I needed to do next) No way to report on thoughts with checkboxes in the notes. A report where you click on a thought and it shows the results in the plex would be perfect for this. /Sigh. Accessing saved reports is a bit cumbersome. I used thought types for completed and non-completed tasks and often they should have been a different type, so those didn't work well for my workflow. TheBrain is not on the iPhone or iPad (or any mobile device), and while WebBrain is ok for finding documents now and then, it's not ok for extended usage. I want to have my task list available everywhere. One exception is a repeating office project with specific steps that are required. For this I set up a template thought, add all the links, documents and template e-mails to the attachments, and add the steps in the notes with a checkbox. Every time I need to do that project or task set I duplicate the thought, rename it (my template thoughts have the project type and "Template" in the name), link it to the correct location and I then have all my steps and files I need. I have a couple of links in the TB User KB that is related to GTD, you might find them interesting also.