I think Durán's supreme skillset, experience, condition and ENDLESS GAS TANK of the Montreal bout would triumph against just about every boxer from the Welterweight division, i just don't see anybody coping with the smarts, offense, offensive defense and tricks of RD
I'd favour Montreal Duran over any Welterweight not named Hearns, including potentially Robinson. Not saying he absolutely does beat Robinson, but his chances are real.
At Welterweight, Duran and Hearns is a close one. Same with him and Armstrong. Robinson has too much for him. Not sure about Napoles, Griffiths and Gavilan. Plenty he does beat though.