While I'm far from a historian, I agree with all the above. I think Mayweather is a phenom, and while I really wish he would test himself to his utmost limits, he has acquired quite a laudable resume all the same. I picked Meldrick Taylor for this thread not because of his resume or accomplishments, but because I believe he has a unique set of abilities that would make it difficult for Floyd to win. Just the combination of ATG handspeed and a really bitchin' workrate makes it hard to win rounds against Taylor -- and we saw he could keep up that workrate under tremendous pressure and stress, absorbing much punishment versus Chavez yet still winning rounds. Floyd would have to win the fight with his feet, turning Taylor, countering -- but can he effectively outscore Taylor while countering? With that handspeed. I dunno. I'd like to see it. I really think Floyd would be an underdog here. Styles make fights.
These are all very good points. I've been reluctant to make a pick (although I lean toward Mayweather) because I think it's a very tight matchup. A think a flip side to Taylor's handspeed and workrate was his tendency to square himself up, and "shoeshine" with the handspeed. This could present opportunities for Mayweather to get angles on him and counter.
At his best Taylor was awesome but he liked to brawl when he didn't have to. Vs. Mayweather he could get away with brawling sometimes and not worry about the payback he'd receive... such in his fights vs. Chavez and Norris (a fast and quick, hard hitting JMW who is now in the HOF). Taylor has a good chance. Taylor looked good vs. Harold Brazier, Howard Davis Jr. (draw when Taylor was an up and comer), Primo Ramos x2, Buddy McGirt (KO12), Julio Ceser Chavez (even though he was stopped at the 2:58 mark of round 12), Aaron Davis. He did not look good vs. Luis Garcia (SD) and Glenwood Brown (dropped twice and lost a close decision). After the Brown fight it was all down hill.