I've used a combination of a Palm and Franklin Covey for some time now. Each does some things that the other can't. My Palm syncs my work calandar, addresses, and inbox email. The ease of editing makes it natural for me for keeping a project list and catagorized to dos. That's all with the out of the box Palm apps.
But I have two problems. I need monthly and daily calendars to write on as my tickler system. I also can't take notes on the palm. So I write brief daily notes on each day page, keep track of big events on the monthly calandar pages, and take notes for meetings and set up agendas in a back section. I have a few notes sections in the back for agendas, reference (like an outline from GTD of the weekly review) or inspiration (summaries of useful books). These are things I've just never wanted to use the palm for, because I need to write them.
If there's one thing I've learned, it's use tools for the task at hand. Don't try to force the task to the tool.