I use a combo of both. I use my PDA for calendar items and things that have to be done that day - I can share my appointment calendar with my two AA's. I use paper to do all of my projects and next action items. This gives me quick retrevil and input. This gives me the best of both worlds. I can drop my PDA into my pocket and attend a meeting and make appointments on the run, I can make notes on an "in" page and it is ready to be filed.
One of the best things I did was to take an old A-Z phone tab from my Covey days and I use that to put all of my projects in order so I can find them quickly.