Stick with Legacy Refworks. Legacy RefWorks will remain available for use through the end of 2018. If you are planning to graduate or will leave Rush in the near future, it may not make sense to transition to the new system.
If you already have a project going in Legacy RefWorks, you can open an account in New Refworks—but maintain your Legacy account until it's complete. ProQuest does not recommend moving active projects from Legacy RefWorks to New RefWorks.