IK is really useful when creating your own poses, or tweaking existing ones. Say you apply a premade pose, but you want to have the figure sit back just a little bit? You can move the body on the z trans, but that doesn't change the position of the figure, it just moves it farther back into the scene. If you move the hip on the z trans, then you will get a variance on the pose that is more natural. If IK is off, then the hands and feet will change position right along with the hip and legs and you'll havbe to repose the feet. If you were going to do that anyway, well that's fine, but if you just want the legs and hips repositioned, maybe for an animation, and you want natural looking movement, then you turn on the IK, and when you move the hip, the legs will reposition with the hip, but the feet stay right where they were. Hands and feet are a PITA to pose, so when you've got something you like and just want to play around with the posioning of the figure, without disturbing the hands or feet, turn on IK. IK is alo used best with the transition dials, to get the hands and feet into approximate positions. They will probabley look pretty mangled when you're done, but then you turn off IK and tweak the parameter dials to where you want them. I have found that creating a "ZERO" pose for the hands is very valuable. You simply set the hand parameters (IK off), and every finger joint parameter to zero, then save it as a hand pose. This will help bring you back to a basic starting pose for the hands after they've been mangled by IK posing, or frustrating hand posing sessions. Sorry; I tend to ramble. Hope this was helpful to someone.