I remember watching a documentary (I think) as a young Pancake on either OutKast or rap in general. Maybe it was their Behind the Music? Well anyways, they talked about how they'd run around the block of their studio reciting their lyrics. Some interesting stuff about them and Organized Noize, too. Their ON era was probably the peak of rap for me personally.
Regarding the Andre/Big Boi disparity, this article details the particulars;
http://www.grantland.com/blog/hollyw...wait-never-was