I've enjoyed reading this post and have my own tale to tell on this subject. While I won't bore you with the all the details. I used a FC paper system for years. In 1998, I heard abut a thing called a Palm Pilot. I was using a Zaurus organizer at the time, so saw no need to change. But with a major job change, I decided to also change my system. I dumped my binder, used a Palm for a few years without GTD, got frustrated with it, and went back to paper. That's didn't help me either because the issue was not the tools I was using , but the system. I ready David;'s book once, applied a few of the ideas, bought a Pocket PC, fell off the GTD wagon, re-read the book, jumped back on, and have not looked back.
I now use Entourage as my trusted system, with an iPAQ 2795 for my portable digital capture tool. I also have a Notetaker wallet I carry with me just in case. I keep a 2-page per day Daytimer on my desk to capture stuff I wish to record as I talk on the phone, participate in meetings, etc. I deal with those items when I do my daily mini review. All goes into the Entourage and is synced with my PDA.
I've been back and forth on trying to find ONE system, but now realize that a combination of paper and digital works best for me.