You may need to ask a few questions before making a decision.
1. Would there be any value addition with upgrade??
2. How many apps do you have in PB 6.5 that need to be migrated?
3. Cost of migration?
4. How long do you plan to use these?
5. Importance of these to you business?
6. Any new features of PB 10.x that you would be using in your apps that would improve business?
As far as I know, upgrading could be fine, especially as PB does not support older versions of PB. But if its not critical its fine. Currently we are migrating from PB 4.0 to 10.x PB 4.0 is no longer supported, however we are not having any major issues during migration.
Migrate if you really need it. Else let it remain the same. Don't fix it if it ain't broke.
- A0C61ZZ