When it comes to testing best practices, that varies from company to company. We certainly recommend testing as much as possible. Furthermore: Salesforce does not allow reverting back to prior versions of managed packages. Skuid always recommends installing new versions in a non-business critical sandbox environment to test all mission critical functionality before installing into a production environment. We also recommend that you update out of date themes when you upgrade. Thanks again for helping Skuid become an even better product!