I breastfed all 7 of my kids for a full year some of them at the same time. No ear infections in our house. Whenever I did need to use a bottle, it was the playtex drop ins with laytex nipples. I never had any trouble getting any of them to go back and forth between breast and bottle with these. I found the angled bottles awkward as the baby had to lay a very specific way to eat, and I had squirmy babies.