Hi,
I tried removing my daughter's bumper at about 12 months, but it didn't work out because she would bang her hand or head against the wood and wake up. I also worried that her leg would go through the slats AND her pacifier kept falling out of the crib. So I kept it in until she learned how to stand on it to try to make an escape (closer to age 2?) But now for my new baby, I took the old bumper out and bought one of the new "breathable mesh" bumpers. It makes me feel safer about SIDS, but it still protects her arms, legs, and head from the slats. Also, when they get bigger, they cannot stand on the mesh to climb out. I bought it at babiesrus for about $20. I've been happy with it, and wish they had made them for my first daughter.