Thanks for sharing! It was really cool to see Prometheus with new footage. It was almost a fresh experience, again.
It also made me ponder what restorations I would make.
Personally, I only would have added the following:
• Janek's Christmas talk
• Milburn finding the flatworm
• Janek's and Vickers' conversation about "pushing the button"
• Extended scene where the Engineer plays with the chandelier, finds Shaw behind the counter, and she uses the axe on the Engineer before unleashing the Trilobite
Those are the only deletions that I think about genuinely enhance the movie without upsetting the pacing too much. My main quibble with the Workprint is that it's very long.
The Our First Alien scene makes Milburn much more sympathetic, and provides a necessary shared moment of wonder before the horror begins.
Janek and the narrative really need the "pushing the button" scene to be restored - badly. This was the most harmful cut to the movie's narrative. Without it, Janek does not have an intrinsic motivation to sacrifice himself. It also explains, eloquently, how past experiences "program" the characters to interpret events a certain way. Janek's extended dialogue about Christmas with Vickers further strengthens their characters, making them more sympathetic, and developing their relationship slightly more before they hook up.
The axe fight is the second-most harmful cut they made, overall. It is not only incoherent in the theatrical version, but it robs the movie of a movie satisfactory climax. It also gives up more of the Engineer, rounding his character more by showing his curiosity before he unleashes his wrath. In the theatrical version, the Engineer comes across as more of a murderous brute. This scene really adds a lot of dimension to him without forcing him to speak.
I firmly believe that Scalia harmed the movie's narrative a great deal in order to make it pacier. It only needed to be a few minutes longer to be substantially more coherent and satisfying. Being 10-15 minutes longer would not have harmed the box office.