How would Floyd Mayweather fare in the current jr. middleweight or middleweight division?

First of all, does Floyd's body look as if he can make that transition to middleweight without being severely undersized? I think he could come in 149 or 150 for a junior middleweight fight and still do well enough. How would he do fighting at 154 amongst the likes of Saul Alvarez, Pawel Wolak, Vanes Martirosyan, Alfredo Angulo or Miguel Cotto? And if he could successfully transition to middleweight, how do you guys think he would do fighting the likes of Sergio Martinez, Paul Williams, Dmitry Pirog, and Julio Cesar Chavez Jr. Who do you see as his biggest threats in each of these divisions?