First I did no bumper/
Then I did breathable bumper.
now we have reg bumper.
I had so many issues, bumping heads, getting stuck.. the breathable didn't work for us. When she was small and not rolling using nothing was absolute best. Bumpers can lead to suffocation and are believed to have involvement in SIDS (don't quote me though)
I debated the bumper issue and lost sleep over it so very much. But getting legs stuck and bumping heads was just becoming too frequent that I put it on and eventually I calmed down. Once she got older it got easier suffocation and SIDS becomes "less" likely.