Amir definately has top notch technique and speed. He does lack the chin though, that is always the worry for him and Zab had been known to hit with some ferocity.
Mayweather V Pac, I have absolutely no idea who would win that one. Both are the absolute nightmare style matchup for the other. The only guy on their level out there at the moment is Nonito Donaire but he is busy decimating all the smaller guys (Gamboa is the big threat once he gets to 126).