I was a devoted Day-Timer user and spent about two years weighing the pros and cons of going to the Palm. When I made the switch, I totally made the switch (or at last almost so).
I do carry a memo pad in my pocket (which doubled as a credit card holder, place to put receipts, etc. I do not carry a wallet). I capture when I am really on the fly or in one-on-one meetings (and not really worry about neatness or details because I am going to dissect those notes within a couple of hours anyway and put it all in the Palm or Outlook). In meetings of multiple people, I use my Palm.
That being said, if I was giong to hang onto one piece of the Day-Timer, it would be the right hand page. I think I would go to a simple journal (so that the whole thing is a right-hand page). You could then use parentheses on entries in the Palm to refer you to your journal (like Dr. Hobbs suggests).
I also keep unifying principles. For me, it's a memo. I have thought about makig reviewing them a repeating task that comes around every month and the list of principles would be a note attached to the task. Just a thought.