DannyD the ability to raise and lower the ball is the desire for using the 3-point hitch model. Of course with that comes some safety issues(tongue raising 3-point, weight distribuition higher than axles etc.). The Bad River design takes care of the tongue raising issue.
Here is another version, that I had built by a local fab shop. I don't move loaded trailers, and my land is flat so I don't worry about the safety chain to keep the tongue down.