Hi Sean,
The minimum DNN version required to run SmithCart v5.20+ is DNN 6.1.5 so you should be okay upgrading to the latest version of the Cart.
Important: When upgrading, it is always recommended that you first do the upgrade in a test environment and make sure you have a full backup before installing on your live site in case you need to rollback.
Please also see the Upgrade Notes available at the following link:
http://www.smith-consulting.com/Forum...
We are also available to assist you with the upgrade of your Cart. If you would like our techs to perform the upgrade of your Cart to the latest version and get your store back up and running quickly please see the Module Upgrade service available at the following link:
https://www.smith-consulting.com/pd/P...
Please let me know if you have any questions.
Thanks