Things to consider when migrating from Exadata to commodity hardware

My client is looking to move from an Exadata system to non-exadata and like to setup a test-case. Looking for any list of things to consider prior to the migration. Another way to think of this is, how can i show what benefits Exadata is providing now (HCC, storage scans, etc)? Also, generally we use dataguard to clone when migrating to/from hardware and not sure if there is a method if HCC is used.

Thanks for any help and/or recommendations