There are also a few drawbacks. Below you'll find a list of both, as well as a URL that contains leaders in this field. Things can become a bit more complicated in a hurry. Issues such as database management and check processing can be tricky. Be sure to ask for full details of the entire process before you sign with any solution provider.
Cost is definitely higher, especially the up-front costs.
However, these costs can be justified in many cases, considering the time and manpower you may save in the long run. Most affiliate management systems use cgi scripts that automatically generate URL's for new associates. While this provides for automated signup, these URL's will not be spidered and indexed at many search engines. You can sign on associates more rapidly and grow a larger force of resellers. You'll enjoy the automation and online management of affiliates.