I've heard before that internal memory is faster and uses less power, but this is the first time I've heard that an internal battery lasts longer. I'd like to see proof. Even if it is true, I need a replaceable battery for these reasons:
1. I carry a spare when I know I won't be able to plug in all day.
2. At some point batteries no longer hold a decent charge and need to be replaced. I have stopped using phone batteries that were less than 2 years old which was before I was ready to replace the phone. I will not buy an iPhone or Razr for this reason. It's one thing to send an iPod away for a $65 battery replacement (way overpriced, by the way) but who wants to be without their phone for a couple of weeks while the battery is replaced?
3. At work, we sometimes attend meetings where it is a requirement to power phones off and remove the battery to prevent spying. I know it's a remote possibility but I don't make the rules.