This is a major change, which should bring the following advantages:

• easier to wrap a ForumManager or other component, for instance to make it "cache" values.
• likewise, allow other implementations to (partially) use other data sources than the repository.
• simplify templates, abstract them from the knowledge of the data structure.
• simplify the API in general, for the same reason.

It should still be possible to use extra "properties" on nodes, for instance by subclassing those new beans.