When one note is off..

That is an interesting observation.

Walter's one note off statement seemed broad enough to me that it could apply to more than one aspect that applied to David.

dk yeah i agree, I think Walter was very politely suggesting to David that he was nuts.

Scrib I like your idea about the Covenant colonists as David's symphony, especially with him strutting through the hypersleep pod deck with that song blaring! 

Walter is simply letting David know that he is faulty, and small faults have big consequences. Look at how Hannibal Lecter regards the flautist in Red Dragon, the follow up to Ridley's movie Hannibal. I'm sure Ridley would have seen and remembered this scene.

Scrib - Lovely thought.

I believe that EVERYTHING said in Prometheus was for a reason.

Same with A:C. Keep it up. The evidence is there. I am sure of it !!

Interesting take on those two lines... i can buy into this yeah.

The Xeno part about how easy it was to kill, i am not sure about, a lot of Alien Fans did not like how easy Aliens and Alien R and AVP made the Xenomorphs Cannon Fodder.... where was Alien and Alien 3 gave the impression it was one tough cookie... we have to remember in Alien no one actually had any choice as far as attacking it, so it was never tested.. apart from the Harpoon.

RS had said the Xenomorph in AC would have Regenerated itself, even after the one that got crushed by the Lander, Crane etc...  a odd statement that contradicts most Alien movies....  apart from maybe Alien and Alien 3

But then these could be Davids more Advanced Xenomorphs that are different and can regenerate?

I do HOWEVER feel the "When one note is off David, it eventually destroys the entire symphony"

If i am looking into how to interpret it a  bit like you have, i feel could allude to maybe that despite Davids Work to Create Perfection it only takes one Flaw in his Design to completely Ruin the whole Plans David had.

We see the Engineers had tried to create/harness similar related Organisms as Failed... and so i think David in his pursuit of Perfection could Evolve the Xenomorph or do something that then sees them get out of control and David Ultimately like the Engineers before, creates something that can not be controlled and this leads to Davids down-fall

A Theme that the W-Y Company and USM try to also gain in the Franchise that always ultimately leads to their down-fall...  The Xeno-Virus/Xenomorph Can not be Contained, Controlled or Harnessed.

I feel that Alien 5 was to touch upon yet another Failed attempt at this Urge to Control the Xenomorph too.

I think the failing or note that is off will be the composer, david, and his inability to control his orchestra