Yeah, I'm going to have to agree with Nick on this one. I was on the animation team, but got to watch all the mechanical guys work out their stuff and then assemble it all.
The ONLY problem that you have to watch for with sub-teams can be rivalry. It's mostly in fun, but some people feel their work is more important than other's, but when it comes down to it, everything plays a role, and without one part, the rest wouldn't be the same.
As long as you watch for the rivalry thing, subteams are a great way to get a team focused. And as far as animation, we broke it down even further. We had character subteams, environment subteams, storyboard teams (although some teams consisted of a single person
). Anyhow, hope this helps too.