We are looking to setup a knowledge base that stores troubleshooting information, answers to frequently asked questions, how-to articles and user manuals. A search engine is required used to locate information in the knowledge base, or users may browse through the categories. It should come with source code so that we can extend its functionality as and when required. Do you have suggestions? I've shortlisted the following products and need help to decide the best among them. We have about 15 staff members that will need a client license to add/manage content in the knowledge base system. We also need to separate the content for internal employees from public users (customers and website visitors).

1. Interspire Knowledge Manager (Discontinued Product)
2. PHPKB (Pretty Nice User Interface and Features - Impressive List of Customers)
3. KBpublisher (Very basic looks, seems outdated)
4. HelpJuice (Comes only as a hosted service)
5. WebsiteScripts Knowledge Manager Pro (Very costly, cluttered web 2 style interface, has almost same set of features as first 3)

Have you used any of them for yourself or for a customer?