I once watched the extended cut in a cinema, all in one sitting. If I remember correctly, we started at 9 in the morning and went home after 10 in the evening. It was really cool. There weren't many people attending. We got Chinese takeout in between and ate it during the second one, the cinema didn't care about people bringing in food. Some people a few rows away looked at us annoyed. Might've been the smell, but I think they were just jealous that we had real food.
Sorry, that one I'm not familiar with. Probably similar goals, although I think M4 is supposed to be one of the most ambitious. It certainly radically changed the tone and pacing. I didn't even bother finishing the original trilogy when it came out I found them so disappointing and generally boring.