Re: Brook v Khan - How would you split the purse?
No, Brook wouldn't have the right for more than 50-50 IMO. Realistically, if it's going to be billed as this big domestic grudge match, most of the publicitly will come off Khan's back. He is the one known by the general public, not Brook.
EDIT: I disagree with you that Khan could not feasibly get more than 50-50. If it happens and one of them does get the larger purse, I think it would be Khan before Brook.