We are using 5.3.1 All good from our point of view.
Your best bet for upgrading successfully is to follow the documentation on the McAfee support site.
One thing to always double check is the components that are no longer supported, the UpgradeCompatibility tool bundled with the ePO install is very good for flagging any potential issue you may have.
Thanks. But what is good way to migrate on 5.X McAfee agent - update first ePO or agent itself?
My own personal choice would be to check if your current agent version is compatible with the version of ePO you want to upgrade to.
If so upgrade ePO first, check all policies are still being pushed out correctly and then upgrade a few agents and carry out some testing.
Be aware that if you are running MSME/HIPS/Encryption etc. the agent communication to ePO could also be affected by the upgrade.