I am also confused
After reading all these articles, I felt the anwer is
"change the compatibility to 120 and test to work new CE"
Please find the below links
http://msdn.microsoft.com/en-us/library/dn600374%28v=sql.120%29.aspx (which is provided by steve jones)
1st point is
Upgrade all existing databases to use the new cardinality estimator. To do this, use ALTER DATABASE Compatibility Level (Transact-SQL) to set the database compatibility level to 120.
5th point is
If your workload is running with database compatibility level 110 and you want to test or run a specific query with the new cardinality estimator, you can run the query with trace flag 9481 to use version 120 (the new version) of the cardinality estimator. To run a query with a trace flag, see the KB article Enable plan-affecting SQL Server query optimizer behavior that can be controlled by different trace flags on a specific-query level.
but is different in the below links