Without a doubt .... Richard Dennis was a great trader during the time he built his fortune and he is someone that anyone in this business could learn quite a bit from. However, I am not sure that he was the greatest teacher. He did give wonderful opportunities to a few young people at the time and some of them went on to successful careers in the business. From what i remember of the turtle endeavor, many of the techniques were fairly standard ideas.
Go to originalturtles.org The full turtle system is disclosed there free of charge by one of the original turtles, Curtis Faith.