Is this a one time thing, or might happen more times? I would say that at
least voice connection would be productive. I haven't that much experience
with video conferencing, but a medium where people can react at the same
time they can think would be important. (although after too much time,
even the fingers are faster than some heads)
How about voice connection for general talk + an irc chat for small, fast
questions? We can also send a group foto with skype, so that everyone
feels the warmth.
Marshall McLuhan would strongly disagree with you, as do I. The medium
with which you communicate has a very strong impact on the
conversation. That does not mean that it is the only influence. There
are many things that lead to a bad meeting, and from my experience of
having many meetings in person, on IRC, on IM, on phones, on voice chat,
on video chat, and many different mixes above, I am a strong believer in
high-bandwidth communication like voice.