There are many ways to improve query plans using hints. However we'd need to make sure that an un-hinted version of a query performs reasonably well.
To confirm that CBO plans are reasonable with and without hints we should compare runs of the CH2 queries with and without hints (at a DGM scale).

1. Run an RBO version for each query (manually structured query to optimize performance).
2. Run the original CH2 query.
3. Run without skip-index hints.