I use Life Balance successfully with a full GTD implementation. I use symbols to distinguish my projects from my next actions and I can review either during a weekly review.
A minor annoyance is that I might need to reference a Memo (I use Palm Memos...I don't want to use a note as the note deletes when I delete the Next Action) or I might need to go through a Checklist (I use ThoughtManager for my checklists).
I wish I could "hyperlink" my next action to the relevant memo or checklist. Currently I have to get out of Life Balance and then push a few buttons to get to memo or checklist.
Does anyone know of anything that does what I describe? I'm tied to my Palm and do all my tasks off of it rather than a computer. I do use the computer for entry and backup -- I use a Mac. I don't think ThoughtManager syncs with a Mac so it's an orphaned application with no back up.