Its interesting, I find a website saying he received kyoshi in a style called Goshindo, also stating he spent 14 years at the ryu's hombu in yokohama (http://www.samuraisports.com/about/danaabbott.html)
but his book, cutting through the mystery, implies that he received kyoshi in toyama ryu...
I have never trained with him or attended a seminar either way so I cannot comment on his actual ability or credibility. But my dojo does do chanbara for fun and his "actionflex" come with an outstanding warranty
but like pjsmith said, I dont see chanbara as having any real japanese swordsmanship context.. it is fun though..