My experience with Poser animation is largely limited to making .AVI's of my suction-dredger-submarine model aiming and untelescoping its suction tube and sucking up a scuba diver who shouldn't have been there at the time. The suction tube involves an IK-circle (= an IK-chain whose goal is IK-parented back to a part of the same model), and I remember that the flexible part of the suction tube (which is an IK-chain and of many parts with the curve property) sometimes twitched oddly or went into zigzags because of funnies in the way that Poser handles IK-circles, and I had to go through the run adding more and more keyframes to keep it in control. That, and nuisance because I can't change a model's parentage or a part's IK-parentage during the run.