I breast fed and supplemented with formula as well with my son. We started with Playtex Drop ins and they were great - I loved the convenience of disposing of the drop in liners. I eventually became tired of having to buy the drop in liners and switched to Platex VentAire and they work great as well. No problems with going from bottle to breast, and even though the bottles may require more assembly and have more parts to put together than some other bottles, I found these to actually be easier to clean than other bottles. Design of the vents causes baby to swallow considerably less air than other bottles we tried, which means less discomfort for baby. So, overall very pleased with this bottle and will use again!