Switching Rainman and Ward - workable?

This is one of those films that no matter how many times you see it, it never gets old. Whoever did the casting for this film did an incredible job - just the right amount of looks and behavior from the redneck hillbillies to the FBI agents. Dafoe and Hackman did a great job and if Hoffman hadn't been nominated for Rainman, Hackman would have won. I can't believe Dafoe was not even nominated. This is why I've stopped watching awards shows years ago.

Question - if Hoffman had played the FBI agent in this film and Dafoe had played Rainman, would it have worked? Do you understand what I'm getting at? If you do understand, do you know what I'm getting at? Is it a relevant question, crazy, or merely strange?