The Avent ones have always peeved me off cos they leak which is super annoying. Tommee Tippee i used with DS2 without any dramas but it is interesting what BOC had to say because DS2 was a late talker until just recently. With the Tommee Tippee ones also i never had any problem switching between breast and bottle with him. Maybe he was just a kid that didn't care where the milk come from.