I definitely agree some websites take more than the 40% - and 60% is a great deal. With that said, some companies do offer more. I don't think, though, openly discussing the payment other websites give is a good idea.
Why not? If we are going to open up the flood gates for people to self publish for profit, then I think they should be given the information about what else is out there in case they get itchy about not getting a good deal.