Yes, its been a pleasure working with WebBilling, Joe & Ines are good guys and their tech staff are very helpful. They have easy to follow integration documents available for NATS 3 & 4.

Are you guys are using Epoch for your affiliate program? I am not sure if they are integrated into Epoch's cascade systems (I have never used Epoch's cascades). I will ask one of the WebBilling guys to respond here to help you out.