I am 100% for NATS. I've been with SexDateCash for about 3 years and we have had them since the beginning. The interface is very easy to use, the customer service people must be vampires because someone is ALWAYS online and their KB (help center) is written so easily that any N00b could understand the simple directions.
I've used NATS, I've used another company which I will not name and I've used custom built backend. I wouldn't trade Nats for the anything.
