Bear in mind a few things when making this decision -- Flex will not have an 8.3 container image, it will be an 8.3.0.1 container released with the next Flex platform release. The 8.3.0.1 release also executes on things that were made possible in the 8.3 base release, and NetBackup appliances will release 3.3.0.1, not a 3.3 release.
So while I frequently say 'yea and amen' to what Cliff says, I would consider moving to 8.3.0.1 rather than just 8.3 if you are an appliance-only environment, Flex, or have plans to utilize immutable storage in the future.
I encourage everyone to talk to your partner and/or Veritas SE to come to the right course for your environment.