After reading this thread do you have an urge to own one? If you do go buy one if not, don't. I can't imagine THIS was the only place on the net to find out about this tool. Keep looking and you may find someone who is better qualified to answer your questions.
I am sorry, I didn't use it enough to give any real answer to you. I did't get the training, I have no idea other than what has been expressed in this thread that is a number of years old now. I have not touched it in any way shape or form since that first time I played with it.
All I know is I see PDR guys do some amazing work without it, you make your decision.