Robert, I think you have excellent reasons behind your choice of the tools you've chosen. I'm quite certain they all work well in your own unique expression of GTD.
However, I'd like to suggest an analog journal and pen for your toolset. Here's why.
It's an Escape from Digital
First, I think a journal and pen can provide you with an escape from digital life. I've found my journals serve as an outlet through which I can step away from my pixelated world. Even if the escape is spent on a 20 minute sketch or capturing a passing thought, my analog moments help provide perspective outside of my daily tasks, actions and appointments.
I believe you might benefit from just a few hours away from the office with a journal, a nice pen, some good coffee and your thoughts. A few hours of separation from your hectic life might open your mind to different approaches to the same problems.
Secondly, writing with a good pen on quality paper is so relaxing. Whether I'm writing or sketching, I find my attitude changes when I'm using analog tools. I use a touchscreen with my Tungsten E, but it lacks the drag, the feel of ink drawing out, the texture. There really is something soothing in it, which I haven't been able to recreate digitally.
Finally, knowing what I put down on paper is permanent plays into this sense — no undo. There's something risky about this idea, which seems to bring out clearer thinking in my work. Once I know that the next stroke can't be undone, my mind seems sharpened.
I believe in analog journaling and sketching, but I also understand each person must come to this decision on their own terms. Realizing the value of analog journaling and sketching took nearly a year for me — maybe you're not at that point, maybe you'll never be.
All I'm suggesting is that you consider the approach. I believe the use of an analog journal for big picture thinking — just 15-30 minutes per week — could provide a new way of generating ideas and capturing thoughts.
Okay, so I'm a little biased here, but I'm sincere.
Keep up the good work Robert! :-)