Currently, the search service unique implemented returns DocumentResultSet, that serve no purpose any more since they are rewrapped in SearchPageProvider anyway. The implementation is in need of overhaul too.

The Search Service and its backends must speak the ResultSet/ResultItem API only for consistency and flexibility. Translation to document model can very well be preformed by the document provider at the top of the stack.

API must be clean for 5.1 whence the relatively high priority. All this stuff is extensively unit tested, hence the risk is low.