Just wondering how many of the Analyzer(s) and QueryParser variations, which where moved in Lucene 4, we could delegate to transparently.
User code typically uses these directly.

Delegating as in creating classes under the lucene namespace in our code which will then delegate to the new Lucene 4 implementations? I don't think this is such a good idea. I would think we are better off letting the user migrate its native Lucene API use.