Debussy, to me, is a particularly fascinating composer and one of the first that I really fell in love with. His music always seems to have such charm, such grace, such color and originality. I have previously posted on his music here and here. Sadly, he never wrote for guitar, though there is a wonderful piece by Manuel de Falla for guitar written as an hommage to Debussy.
But back to Debussy. After listening to those performances of Syrinx do you say to yourself, "but they are all exactly the same!" Or do you notice differences? If you look at the score you will notice a tremendous number of performance indications apart from just the notes and rhythms. Musicians can be justifiably proud of having created a notation system that can really capture the evanescence of sound on paper, but in the interpretive details, it is still merely a sketch. For example, composers often give a precise metronome marking, but at the same time, they modify this with various words like ritardando and accelerando indicating, respectively, slowing down and speeding up. Beethoven is reported to have said that after the first four bars you are on your own. But Debussy gives no metronome mark for Syrinx! He just says: Très modéré: very moderately. And the score is littered with dozens of other indications that all serve to derail a metronomic performance. (There are reports that originally Debussy even left out barlines in the score.) For example, there are breath marks, indicating short pauses, fermatas, indicating holding the note for an indefinite length of time, tempo changes, indicating slightly faster movement, and the marvelously ambiguous word rubato meaning simply don't play in strict time. There are also a lot of dynamics in the score indicating louder or softer, but, as usual, in an indefinite way. So the upshot is that you can play this piece in a thousand different ways! Mimi Stillman is planning on recording a mere 365 different ways!
Musicians do this sort of thing all the time, of course, though they usually don't make a record of it. If you are learning a piece, you play it every day. Every time you play it, even if you are trying to play it exactly the same way, it will be slightly different. If, like Mimi Stillman, you play it in different locations, you will play it differently because of the resonance, or the humidity, or the temperature or simply your mood. As Heraclitus (c. 535 BC - c. 475 BC) famously said:
πάντα χωρεῖ καὶ οὐδὲν μένει" καὶ "δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης"
"Everything changes and nothing remains still ... and ... you cannot step twice into the same stream"