The Trade-offs Extranets aren't without caveats. For one thing, the security may be rudimentary. Most extranets, for instance, don't encrypt the passwords and user IDs sent across the network. Your own customers may not protect their user IDs and passwords as well as they should. In each case, the result could be unauthorized use.
Cost is another pitfall.
You may have to pay to maintain two sets of Web content, one for your public Web site, another for your extranet. Because they're customized, extranets require regular maintenance, not to mention back-end integration with your existing information systems. They may not be cheap to maintain, but extranets permit you to support customers better. That tends to increase business and reduce customer turnover.