Double post, but I've just had another thought.
Thinking about the AviSynth script, and the sample of the Greedo subs that was posted - although the font, drop shadow and positioning are great, don't you think that the subs themselves look a little too "clean" when compared to the rest of the picture?
For a true simulated theatrical experience, do you think that the subs would look better "dirtied up" with a little added artificial film grain over the text?