First of all, I'm impressed at how much of the GTD system you appear to grasp for not yet reading the whole book.
I have found in my experience it's a learning process to see how best to apply GTD for you and your needs. I started with Evernote using TSW as my base. I slightly modified TSW to my needs.
I love Evernote because it is accessable on my iPad, iPhone and my desktop PC at work. The mobile platform Evernote has created is ideal. The one thing I don't like about Evernote is how to create a project. Each step needs to be a separate item in Evernote.
So, I'm exploring NirvanaHQ.com. I love the way their system works for Next Actions AND Projects. Each line in a project also becomes a Next Action. It's just perfect on my PC. The downside?? Mobile. It's just not there yet. It's fine for entering a Next Action using my iPhone or iPad but I need to go back to the PC to really clean it up and get it in order. THAT means, more time needed. I don't like a system that isn't simple...I'm doing GTD to keep things simple.
Since NirvanaHQ is new and I have seen what they have done so far, and that they are working on the system, I've signed up for a year in the hopes they follow through with a great mobile platform. If they create a great mobile platform...I would become a huge NirvanaHQ pusher!
iPad, iPhone, MacBook, PC; all running Nirvana, iCalendar and GMail
Mastering Workflow (2012 & 2013)