I've heard the piece played back by my laptop, but hearing a composition live for the first time is a unique experience. The effect that it has is unpredictable, despite familiarity with the score. There is, therefore, an element of chance about it all and that I do not fear. What arises depends on the written notes, but that is only a start. Who turns up to a rehearsal and how they play the music, not knowing themselves what to expect, makes the potent magic potion. In addition, I simply do want this element of chance and the coincidence of circumstances to inform the outcome.
Including rhythmic impro. and unpredictable gaps of silence could create a sort of hothouse, encouraging growth. That's alchemy. It's all to do with process. The end result will be success or failure or something inbetween, but, hey, who cares, it's the process that's the driving force and the way the contributing musicians interact that makes it live. The conclusion is completely secondary to the amazing process that leads up to it.