Okay, saying “it’s one big movie! It’s just cut in half!” is stupid whether applied to Kill Bill or Matrix or, I don’t know, American Pie, whatever. It’s a bad idea to make a six-hour movie. Have you ever seen a six-hour movie? There’s a reason for that. It’s a worse idea to cut it in half. It’s bad enough mentally breaking out of the film long enough to take a five-minute bathroom break; I don’t see why a six-month bathroom break would be better.
If you want to make a long movie, make a three-hour movie and end it. If you want to make several movies, make them short. It’s not hard. Just don’t let any action sequence last longer than five minutes, and kill the freaking monologues.