Over the years I have run across an amazing variety of custom and consultingware CMS platforms installed with clients. One question I get asked almost everytime is should they switch to a commerical CMS product. Now I know there is an appeal of having something tailor made to your organization, but does that really outweigh the potential issues you might have in the future? My standard response goes something like this:
Having a custom CMS presents a twofold problem for its owner and end users. It is easy to become embroiled in activities that go beyond just managing the content of the site. In many cases, you end up having to fulfill the role of product manager for a custom product with an install base of one. You also risk being left with limited-to-no support options if the relationship with the system creator sours (or in the case of an internal developer, leaves). To that end, having a commercially-supported CMS allows the content creators and authors to focus on the site and not the overhead of supporting and maintaining a one-off system. They also benefit by belonging to a larger community of users who receive formal product support with regular product updates.
This is not to say there are some scenarios that would warrent custom work, but if you do decide to continue with or create something custom please think about what you are really taking on, its risks (and benefits) and what it truly costs.