There's a very interesting looking doco coming up about Michael Mann's The Keep.
I really enjoy this film, despite its flaws (Ian McKellan acting like an old man isn't his finest hour). It's got great music and design, and some memorable imagery and a nice dream-like tone. I really liked the smoke enveloped creature phase they have. And the scene where the Germans unleash the creature is very nice, i think.
I'll be getting the doco when it's out. It doesn't really matter the novelist F. Paul Wilson hates it, but the fact Mann isn't overly keen on it is a bit disappointing. I read the novel and enjoyed it, i recall, but it's definitely very different in many places.
To be honest i prefer the ending they have in the film that exists than the one that was apparently proposed or was in place in Mann's original cut - that was a happy happy ending - and i like that final image they hold on.
And yes, i'd watch the 3 hour rough cut and enjoy it, probably.