Hi Troy

That is correct you will still be able to access the Totara 12 Appraisals in Totara 14 by enabling legacy Performance activities. and showing historic activities. 

You don't need Perform enabled in Totara 14 to access the legacy activities but you will need Perform enabled to create any new performance activities including Appraisals in the new format which provides more flexibility for creation and reporting.

Regards