Before you save the system property in production change the ignore cache setting to true, so it won't cause any additional performance issues in production when you activate the setting. This is now the Servicenow recommended setting for all system properties added to the system and has been since Rome version. I have modified a lot of the older properties to have the ignore cache value set to true.
Personally I have set the rest debug setting on in production for max 5 minutes. We have 12 application nodes and 5M API-calls coming into the system daily from Event Management. Haven't seen any performance issues, but the excessive logging is off course something you do not want to have running for a longer time period.
When to use 'ignore cache' on 'sys_properties records
https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB1000746
