A filter puts you back to 100 ISO, thus defeating the purpose of a fast film. Besides, this kind of experiment is fun.
Who wouldn't want more options? ECN-II for still photographers would open up a huge world. 50D anyone???
Good points though... if we're scanning anyways, the corrections could be made post, and with daylight film.
So to clarify, there's no orange mask on ECN-II films, is that right?