I find typing notes on a laptop much more effective than writing. Because I can type much faster than I write, I find myself putting the ideas in my own words, hence I remember them better, even if I never look at the notes later. I've never tried a tablet, but using pen and paper, I have to keep looking down at the notes, which is very distracting. With a laptop, I can keep my eyes on the speaker and his presentation. Later, often on the plane ride home, I edit out the many, many typos, which I find is an absorbing way to review the material.