Since I usually get paper in case of a cancelled flight, I would recommend paper, but my understanding is that as long as you have a printout copy of your E-ticket, you will be ok. The key is to have something in writing, whether it is computer printout of your E-ticket reservation or a real ticket.
PS. I just looked at expedia.com today and they had a $10.95 shipping and handling charge for paper tickets on the site. I have never paid more for paper tickets before and wonder if this is because suddenly everyone wants a paper ticket due to the uncertain nation of air flight these days.