I have had a few pieces over the years, been to his shop in Seki City, and am honored to call him friend, but despite all that, his knives still hold a continual fascination for me. His "Hamiguri ba" (sp?) or convex edge, as it is commonly known here in the states, adds an amazing amount of strength to the edges of the models that feature them. I have never seen such sharp edges on such thick stock. Simply awesome knives that have a lot built in to them. they cut well, and have very impressive edge retention. I do not know anything about his heat treating process, but have not had any problems with edge chipping, rolling, or pre-mature dulling.
His favorite steel to work with is OU31, which I also do not know much about other than it being a high carbon steel from Japan, and it being really expensive.
Bill, he is an awesome host, and a good friend. If you'll be at SHOT, and have not formally met him yet, I would be more than happy to introduce you. It would be pretty cool to see two of the best havin' a meetin' of the minds.
Mike