Most of it is pretty healthy. One of the reasons to put discussions in a public policy forum format is that it helps prevent articulation of off the wall positions that are defended as. In that sense the discussion format is clearly working well. But, like most instructors who rely on class discussion, we are faced with the problem of what to do about the ones who don't seem to want to talk. The format helps in this regard in many ways.
Teams tend to pass around the responsibility for the opening statements in the discussion.
And teams are increasingly assigning different individuals to represent their position on the various sub parts of issues. A student almost always has to talk at least once in each topic discussion. But some are still ducking making a major contribution. One of the theories often advanced in favor of the new instructional technologies is that students who do not like to speak up in class will often find something like e-mail or presentation software a more comfortable medium in which to communicate. The problem with those who are not talking stems, for some, from lack of preparation.