I think Cheadle wants a hagiography. Miles is from my part of the country, and musically, you grow up with Miles' stories. You don't want a biopic. Just listen to the music. It's like eating meat. Eat the food, don't tour the manufacturing plant.
A little correction--Cheadle wants the role of Miles. And he could play it any way the story goes. Still, stay away from the manufacturing plant.
I generally agree, but such great stuff was done with Joaquin Phoenix and his work in Walk the Line that you can't help but wonder what could be done with Miles Davis. Musicians tend to be crazy and I'm not sure how much the general public would relate with him. Cheadle would be wise to go in a different direction and try to use modern computer illustration technology to provide a visual accompaniment to Birth of the Cool and Kind of Blue.