Here is a link to a video that has a lot of very fast movement that is Asymmetrical and would cause the Spline to have massive overshoot in it.

Fast Disco movements

It is going to be hard enough to put in all the Key Frames to get something close to the dance moves and then trying to overcome Posers lack of overshoot prevention will make it even harder and then if you had to move portions of some frames forward or backward even more hassle.

It has been suggested to me that I should use Linear. That really is not acceptable as if you had 5 Frames between Keys with Linear they would all move at the same rate. With Spline frames 1 & 5 would be the slowest, 2&4 medium and frame 3 the fastest. If you made a video with Linear your brain is going to say there is something off about it and you probably would never know why other then it looks weird.

I figure if they can fix this problem which as I believe I have shown is already part of the Poser code, and Fix the Layers feature to stop using the KFD value when combining layers then Poser can start to put in some real improvements to make animation easier to do.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13