Thanks for your comment Kourosh. As I mentioned in my post, I still feel pretty new at GTD (still reading the book after a year!). I do find that when I sit and read it it comes together a little more for me and my ideas about which kind of system will work for me coalesce a little more.
I am beginning to think I need to embrace OmniFocus more and get an iPhone or iPod Touch so I can run the iPhone/iPod Touch app as well. Not being able to make my GTD system more mobile and integrated is a barrier.