I understand that IK is not keyframe-able. For the way I use it, IK is not broken at all. I use IK to keep figure elements in place from one frame to another. I select the elements parents and set keyframes and then, after turning IK off, make any adjustments to the figure I think necessary.

I've never had IK NOT 'let go', so I'm not sure what you mean there.  I AM using Poser 7, so this could be some new bug in the newer versions of the software.

One might use IK during segments of a longer production, and edit those IK on and IK off segments together later in an editor.  I do understand that stringing together IK locked elements and non IK locked elements might not always work too well.  I'm not sure that is what the tool is designed to do.

To the original poster I stress that like anything in Poser there is no quick fix.  The program is a tool that requires understanding and some patients by its user.  I would seek out tutorials and read up on any threads here at Renderosity, and keep practicing and playing around with the software.

Best Wishes, all,