Robinson was a huge welter. In terms of p4p skills you can compare them, but I don't give Floyd much chance in a head to head match up. They are both very fast, Floyd has a brilliant defence and SRR a great offense, but SRR also has a huge advantage in size, strenght and power and would likely just walk through Floyds shots and hit him on the arms and shoulders until he cracks.
I believe technically boxing has produced much more skill than SRR. People tend to get offended. The question was who wins NOT who is greater. Now who is greater? SRR and it is not even close. Who wins? Floyd because boxing like any other sport has progressed with time
Sugar Ray Robinson is too gifted, he's probably one of the most complete boxers ever to compete, I can't see him losing this.