You can take a back up of that Data base before upgrade. Now once if you will install BP 6.5.1 automatically Database is upgrading so before upgrading take a back up and if you want to roll back then you Roll back in Data base also..
You can try in you local connection 1st then go for other.
And Update to 6.5.1 after some days once you will see how much stable it is.
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Amlan Sahoo
RPA Consultant
Equinix
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Regards,
Amlan Sahoo