The one thing that is really fascinating about it is that I have always felt that Mccartney and Wonder's voices really worked well together.
I wonder if the director of the Ebony and Ivory video did Paul's Coming Up as well. Interesting to note that Paul had such a malleable voice, soul, rock, pop and anything else he wanted at the top of his game. John and George had that quality as well. I also think that years of singing in a multiple vocal band did help as well.