From what I've seen playing hutball, force shroud on assassins makes them pretty much immune to all CC except pulls or so it seems. I queue with 2 merc healers and another assassin and we dominate hutball with speed + force shroud. The only thing that stops us is when we get pulled by a powertech or another tank spec assassin. So far this has been the only ability that can break through an active force shroud. CCs and knockbacks have no effect when force shroud is active (3 seconds active time, 5 seconds when talented deep tank tree).