Well this discussion most interesting, and has covered a lot of ground in a scant few hours. I don't feel I have much to add to all that, but to observe on one side-issue: I'm utterly baffled at the "but things didn't really happen that way back then" objections to the "O Brother" film. We're talking about the Coen brothers here. They gleefully make knowing, deliberate changes to history and reality in this film, such as having Pappy O'Daniel be governor of Mississippi rather than Texas, having Baby Face Nelson still be alive at the time the movie's set, having Klansmen do a Busby Berkley at a cross-burning, or having a dammed reservoir flood suddenly. They "based" the movie on the Oddyssey the same way "Fargo" was "based on a true story": not at all. They openly admit to never having read the Oddyssey (I think they're lying: they grew up in St. Louis Park, where the schools are quite good).
I mean, come on. These are the guys who made "Bood Simple," "Barton Fink," "Raising Arizona," "The Hudsucker Proxy," and "The Big Lebowski." Anyone who expects reality from a Coen brothers film just ain't been payin' attention, and is missing the point. They're storytellers, not historians.