In this post Emily demonstrates an interesting way to depict the movements of Kuiper Belt objects: http://www.planetary.org/blog/article/00003381/
I like this diagram. It reminds me of lissajous figures on an oscilloscope screen in the case where the x and y signals have the same frequency but differing phase relationships. I agree with the idea of reducing the size of the objects' position and direction markers. Perhaps tiny triangles could serve in both capacities by being oriented to point along the 'orbits'. I would like to see Sedna included since the (so far) unique nature of its motion would stand out well. I think its trajectory during at least the second half of the 600 year timespan in question would fit on the diagram.