[Christian]

I think a key point to properly use GTD is self discipline. You have the tools - OF and a calendar - but it is your responsibility to look into them at least once every day. OF gives you rich features to sort your responsibilities into projects, folders, contexts - but it still is your responsibility to open the "desk" context when sitting in your office chair. It gives you a tool to be reminded that certain tasks need action until a certain date - but again it is your responsibility to decide what is important enough to be "due dated".

What I would find useful to be implemented into OF would be a "daily workload assignment" option. That means am option in every task and project that allows me to specify a date on which I would like to work on that task or project. These tasks would then show up in forecast view, telling me that 5 hours of my Tuesday will be blocked because I want to - not have to, in the GTD sense - work on task X. That would in turn allow me to "block" time for a task on a given date but still keep the actual due date intact so I can be reminded if I fail to finish it for some reason.