Responding to Beth Kanter, who asked me for a comment, so...
Perhaps it works with your audience, but if it were me, my first reaction is: I hate small groups, I hate small groups, I hate small groups.
Although people say that small groups 'give everybody a chance to talk' what they *actually* do is serve to eliminate minority and dissenting opinion.
Suppose there are two options, (a) and (b). Suppose that 4 out of five people prefer (a), but on hearing (b) one of them will be convinced to switch to (b) (this is a *very* common situation).
You have 15 people. That means that at the start, 12 of them prefer option (a) and 3 prefer (b). After the discussion, 3 switch allegiance, so you have 9 people preferring option (a) and 6 preferring option (b). Almost an even split; certainly option (b) is a respectable alternative.
But imagine that instead we split into three groups of 5. Now in each group, four people prefer (a) and one prefers (b). Although one person is convinced, there's still 3 people that prefer (a). So the group moderator reports (a). The results come back from the groups: everybody prefers (a). The preference for (b) has been squelched out of existence.
But that's not all...
The division of people into small groups is almost never random. Often, group leader are assigned by the organizer. Even when groups form on their own, the group leader tends to be the person deemed most favorable to the organizer.
Now you have a situation where, even if more than half of the people have switched their allegiance to (b), the organizer, who is loyal to the original option of (a), will report (a). This completely subverts the will of those who preferred (b), and worse, leave the (b) supporters with no option, no access to the plenary floor (without 'causing a disruption').
I have seen small groups abused so regularly and so often I have some to conclude that when small groups are employed it is almost *always* about maintaining the power of the organizers rather than giving people a voice.
To me, 'giving people a voice' does not merely mean 'allowing them to speak' but also 'enabling them to be heard'. When somebody is shuffled off to the obscurity of a small group, that voice has been stifled, not empowered.
The use of small groups, rather than empowering people, instead elevates a few people - the 'representatives' - into super-voices, and by design silences all other voices (again, any dissent from the official report is 'disruptive').
There is yet another way in which small groups stifle dissent: and that is by the creation of an expectation of resolution.
I was at a meeting where a small group process was discussed just this week, that would take place in a school context. Like everything else in schools, the 'discussion' was being carefully regimented. Three hours were allotted, with the requirement that the groups "come to consensus" in that time.
In my experience, the only way to get people to arrive at a "consensus" on anything in three hours is to run roughshod over their right to voice their dissent. Perhaps a vote may be taken after three hours of discussion. But on nothing but the most trivial of issues should any group (of any sort of diversity) be expected to reach consensus.
What is happening, of course, is that a consensus will be 'declared' rather than reached. The time pressure and the peer pressure in the small groups (where supporters of a minority view will have been isolated from any others sharing that view) will force dissenters to 'go along'. In these exercises, to, there is nothing major at stake - why be a holdout, when the process appears to be so much more important than the result?
Finally, although it doesn't really come up here, I will point out that small groups are often used to ensure that a superiority of numbers conveys a strategic advantage. You see this at policy conferences, where concurrent sessions are held to discuss different issues. I often find myself wanting to comment on more than one subject, but find that because of the structure I can only address one thing.
I have nothing against games like this, other than a passing observation that they may feel a bit contrived. But I really dislike the small group process. Because the most disempowering thing you can do, in any setting, is to impose a structure that ensures that voices won't be heard.
Just my view.