I think Spinks would give Mayweather fans a scare by making Floyd look bad early on as Floyd takes time to adjust to his opponents in the early going. That being said, I think Floyd would completely own the middle and late rounds, winning a clear cut UD or perhaps even a TKO (I think Floyd hits harder than he is given credit for, he's just too conservative to chase the T/KO). Then again, Spinks would have to actually land more than 15 punches a round in this fight to make it remotely close... which I don't think it would be in the end, cause Floyd's a shitload harder to hit than JT, but Spinks probably wouldn't be as wary of Floyd's power. I'd probably be the only person in the world interested in seeing this, just to see how Floyd would handle it.