I am a big Mayweather fan, but Pacman will win by UD. Mayweather has superb defense but I don't think he will throw enough to beat Pacman. If De La Hoya was getting his slow left jab in often, Pacman will get that fast straight left in there too. Probably at will considering Mayweather's shoulder roll is only effective against orthodox fighters.
Its a very hard fight to predict, I'm back and forth but I just cant see how PAC unless Floyd makes him tentative can lose a decision.