i strongly suggest you not use CCBill because lately they have been converting bad i think i heard its down 14% if anyone has them as a payment processor get out will you can.
I do website development work and know a company (Paynetsecure.net) that works exclusively with High Risk Merchants such as adult related businesses. Their fees average between 3.5 - 5.5%. http://www.paynetsecure.net/adult-merchant-accounts-high-risk-payment-processing-services/
Verotel is a leading Internet Payment Service Provider (IPSP) since 1998 and is specialized in online credit card payment processing for high risk businesses. Servicing over 50.000 online businesses with online payment solutions Verotel understands the risks of online billing. You can see more at verotel.com
CC bill is the best processor for adult industry , it's just safe and no complex steps in payments and yeah low fees per transaction..