I used to be a big fan of Guzman but he's turned me off over the years thanks to all his antics. He was tremendous at 122 but my guess is that the fight is called off after Guzman comes in about 10lbs overweight. I think Gamboa has faster hands and more of a killer instinct, while Guzman is adept at fighting off the back foot and has a rock-solid chin. I think Yuri beats him on points.
Very, Very Interesting question! Its interesting because I do not think that Guzman never reached his full potential and we have yet to see prime Gamboa. I think Gamboa is becoming a more complete fighter and might actually do better one weight class above were he is at now. I think Gamboa has the hand speed to expose the flaws of Guzmans game (even though you could say the reverse) and would catch him . . . if he fights a patient fight!