Kahn-Diaz would be interesting but one thing I am positive about. If Kahn butts him and cuts him, the fight will quickly go in his favor. Diaz has problems with blood. It's his Achilles Heel.

Also, Kahn's advatage in dimensions of 5′ 10″ - 178cm vs. 5′ 6″ - 168cm and his reach would hamper the short Diaz.

I'd go with Kahn but I'd get me some nice odds.