With the pin-up poster, each sheet or board is separate. These are typically the easiest posters to transport. This display format does require attention to formatting details so that each sheet or board is uniform with the others. You'll also need more set-up time on site, particularly if you're pinning sheets to corkboard or the wall. Finally, you will need to have the sheets in order so that you can pin them up quickly without worrying about layout at this point.
International conferences typically allow for pin-up posters of some sort to alleviate the problems in transporting large posters via airplanes.