If I understand correctly, this functionality does not help Jackrabbit (makes it more complex), but would allow other projects to store their class files inside Jackrabbit.
So when Lenya uses Jackrabbit: 1. Jackrabbit loads. 2. Lenya's classes are extracted from Jackrabbit and load. 3. Lenya loads. For a performance hit during startup, we gain the ability to store the entire project within the repository. That could be good, because we want everything treated as content. The concern is whether this damages the ability to replace Jackrabbit with another JCR implementation. If it requires special functions outside JCR (rather than built on JCR), we could not use it. solprovider
