I also have Mainstream sites this is what I use
CCbill for Member Access (you don't have to pay a fee if it is Mainstream)
I have a Merchant Account (Non Adult) with Cardservice International for online and EFS for Retail.
If you have a non high risk site (like selling t-shirts etc) Cardservices will not charge you an upfront charge. Their monthly fee is
2.35%
Monthly min is $ 25.00
Customer Support $ 10.00
Monthly Gateway $ 19.95
http://www.cardservice.com
I am not sure if they take adult I never tried it.
I have an outside shoppingcart with cart32 (NON Adult)
http://www.cart32.com
Hope that helped