But I am fairly certain that neither studied with the other. Jim Siska has his own style, he has for years. It evolves, but is always "Siskaesque". I own two of his knives, and they are spectacular. I finally convinced him that he is an artist this year, he defined himself as a craftsman.
Jim has a good full time job, and he is loath to give it up. He makes knives when he can, he can put a few out per year, less than 100, for sure. His realistic wait time is about 18 months to 2 years. If you want one of his knives now, best bet is to go to a show that he attends, or buy one from an internet purveyor. There is a reason that they carry his work, and it isn't 'cause his is a really nice guy, even though he is.
Rados has more of a "traditional" New England Style, in that I mean that his knives are not always distinguishable as Rados knives. His great gift lies in his damascus making skills. His Turkish Twist is worth its weight in gold, IMHO.
Michael Viet was making his own Turkish Twist, and hot bluing it in starting in the late '80's-early '90's. The use of Turkish Twist is the only similarity to Rados that I ever noticed. Michaels's style was closer to David Broadwell or Ron Gaston, IMHO.
Best Regards,
STeven Garsson