Command Poster strips - damage-free for the poster, or just the wall?

CaptionI've got a few posters i want to put up and i've seen many people mention that the best way to stick them to a wall is with Command poster strips, as using the usual blu-tack or something similar tends to leave residue on both the poster and the wall.I've not been able to find any clear answer with whether the poster strips will leave the poster undamaged, I've only seen mentioned of it not damaging the wall. If anyone could give some more information on them that would be great.Are these easy to remove from a poster without damaging it? Would there be any noticable difference to the poster afterwards (e.g. like the residue with blu-tack) or would it pretty much be as good as new?How long do the strips last for when put up?What i have are relatively thin paper posters, they aren't important but at the same time i'd like to have them put up in a way that will mean when i do eventually take them down, they aren't going to be any worse off than they were before.