Take all film with you, at 400 and over it could be harmful. Its true that, at the carry on, the big machines can fuck them up, though it hasnt happened with my 400s. You should try to get them handchecked - even if that may mean that you wait ten minutes and they open all of the films to see what´s inside and they treat you unfriendly - actually my dad missed a flight because he had 40 super8 films, and they opened each and everyone. Try to take it easy otherwise the damn TSA will show you their uttermost disrespect... don´t be aggressive with them, if they ruin your film, you will not be entitled to recieve compensation, they will just hand you a complicated form, which you can fill out if you call a number in Washington. If you call there, the agent will only speak with you after you have recorded your full name. Indeed, all incoming calls are recorded as well.
Needless to say you can feel like in a bad dream. One of the reasons why I don ´t plan to relocate in the U.S.