I was so against crib bumpers but now my baby hits the rails when she starts waking up, I don't want to find her hitting herself on the head when she rolls over so have to start looking for one that I like.
They have breathable mesh crib bumpers if you feel more comfortable using those!
I got a mesh one that is still really soft, and breathable. I like that if she wedges herself in the side, she can still breathe, but, it has soft cushions for the actual wood part.
I have the mesh ones, too. They have them at Babies R Us for a decent price. I like them because they keep my daughter from sticking her legs through the bars, but she can still breathe and be cozy if she's up against it.