Personally, I don’t mind listening to MIDI versions of pieces not yet performed. I have enough performing and rehearsing experience that I feel I can “hear through” the stiff MIDI limitations and imagine what the piece will actually sound like. It’s an aid, and you have to know how to use the aid and not mistake it for the reality. But I’ve also had enough bad experiences playing MIDI versions for people – people who didn’t seem to possess that ability, and who reacted with a visceral dislike to the piece based on its synthesized version – that I avoid playing MIDI versions for others.
Further than that, while it’s one thing to listen to a MIDI file to get a sense of a colleague’s new piece, it strikes me that to listen to a piece that way with the intention of performing it later is an entirely different thing. I’ve had some bad experiences with it. Sibelius (the software) playback has trouble with fermatas, which sometimes get applied to notes they weren’t intended for, and it doesn’t always portray arpeggiated chords or grace notes elegantly; the result being that I have sometimes had to go back and remedially convince the performer that I meant what I wrote in the score, not what he heard on the MIDI file. Of course I could import a Sibelius file into Digitial Performer and sculpt every note, but that’s an awful lot of work for something that isn’t a final product, just a temporary convenience, and the results are still imperfect. Even when such details aren’t a factor, I’m uneasy with the idea that a performer’s first audio experience of a piece will be through a stiffly metronomic version with no nuance. There’s a wonderful process that happens in rehearsal as the players slog through notes whose interrelatedness is still a mystery to them, and then suddenly they hear other parts correctly played in hocket with their own, and everything clicks, and the music emerges from chaos. Then they create the piece from the notation, and it has personality, rather than trying, however unconsciously, to replicate a lousy artifact they heard an mp3 of.
But that process takes time, and when an ensemble is short of time, they ask for a MIDI file to speed the process up. As I’ve written here before, “Efficiency in the pursuit of music-making is no virtue.” But I hate to turn down a request from people enthusiastic about playing my music. Perhaps I’m being too sensitive and old-fashioned about it, and this is the way things are done these days, and I’m curious what other composers do and how they feel about it.