I had someone email me about adult friendly payment processing a while back. It was something like 4.9% but they are adult business friendly. I would be careful to take American Express as they do not allow adult transactions. The strip club I work at has banned the use of AE because they allow a year for charge backs. Most sc add a surcharge for CC to hold a stash for when charge backs happen.
Good luck!
tony@vswipe365.com