Is there any reason to upgrade from version 6.3.3 if I don't do MU [considering retirement in 6-12 months]?
I would say "no".
Also agree.
For the same equipment, network, and setup, versions beyond 6.3.3 are demonstrably slower. If you have several users (above 10-15) it may be unacceptable, and we have had clients choose to hard-roll back.
