The fees we (MPA3 or Nats) charge for that feature along with all the others in the software(s) absolutely makes sense to your bottom line. Proven over years of doing it for a LOT of affiliate programs in our marketplace.
Of course, just cascading billing is good too, but you do need to report the numbers properly, and I will wholeheartedly say that you do need a complete backend to support the cascading billing. IMHO.
