Its more like Duran fighting Barkley. And even if Floyd DID beat GGG, Duran would still rank ahead of him.
If GGG won, everyone would jump up and down about how amazing GGG was, despite having 15-20lbs weight advantage. If Floyd won, everyone would say GGG was weight drained..
If GGG isn't dead at the weight he destroys Mayweather in 6 rounds. Floyd is a lot slower now then he was so can't just avoid GGG, he got trapped on the ropes at times against Maidana, Imagine him on the ropes against GGG!.