@gyuszi debranding your phone would remove some things like if there were games/applications as well as themes and other such things that came with your phone that are only available through branded phones. But i would agree that for the most part its better to have an unbranded one.

@Wally_Dog Cingular would not be able to tell by unbranding your phone at all. but debranding it would remove the settings for internet on your phone, so you just need to add the settings back onto your phone after the debranding to get internet once again on your phone.