I simply cannot see Paul with his victory, he looked great vs Ishida, but he has never faced anyone with the handspeed/technical prowess of May. May UD. Easily.
He'd make Mayweather work for it. FMJ doesn't have enough power to stop Williams from coming in throwing 200 punches a round, so even if he is eating shots, I don't see Paul's work rate dropping, or even him getting discouraged enough to stop throwing, for that matter. This would make for an interesting fight, though. The beast might come out in Floyd.
Williams, like Margarito, is someone who I can see Floyd figuring out and beating with sheer skill, but would have to work for in doing so while answering questions about his ability to move constantly and handle such pressure & volume.