We should do nothing that interferes the composer's future option to publish a work. But I don't see how that would apply. The critical question is the right of the composer to make use of an audio recording done by our group. A simple release form would probably take care of this.
I should think that the permission to make use of a recording of a composer's work by other Virtual Choir members should be at the discretion of the composer.
If these recordings were used in a for-profit way by the composer, the Virtual Choir ought to get a small percentage since there are costs involved in the productions (the performers and sound engineer's time, the maintenance of this site, etc).
Although pleased with my part in the mixing and recording of the virtual choir piece "June" I feel it is not up to the standard expected of a marketable product. Therefore, although it may create interest in others wishing to perform the piece in future, I suspect it likely the score providing any monetary gain.
I was thinking more of future projects. The only use I can envision for these is to demonstrate the piece for possible other performance live. (as you said). I can also expect that some may go up on youtube. As a formality (my background as a video producer) it might be good to get a release?
Just a reminder - this environment is primarily educational and most of us are here to learn and share. We're not a commercial enterprise, and I doubt that anyone in the Virtual Choir is thinking of making money from any of the recordings! Eric Whitacre has a slew of lawyers and all kinds of legal disclaimers, because he is very much a commercial enterprise.
How about for each piece, the composer creates a release form describing what s/he is asking or giving? I think it might be different in every case. Each person who participates should also have the option of having their name included on programs and presentations, or if they wish, they could remain anonymous. In those cases, the participants would need to make that preference known - which could be as simple as posting a note in a VirtualChoir forum. Everyone also has the option of signing up for VA under a "stage name". ;-)