I would be devastated if an hour was cut from Magnolia. It's my 2nd-favorite Anderson (behind TWBB), and if you sign on for what the movie is doing, I don't believe there's a minute that can justifiably be cut. It all works together as a mesmerizing whole.
This episode makes me crazy. I've seen Shaun of the Dead 122 times, and I believe it's truly a perfect film. Against any other movie it would crush, but Magnolia is rying to do more, and it succeeds. It's transcendant—a once in a lifetime kind of film.