User and Grous Migration From 3.1 to 4.1

Hi All,

i am planing to do migration from BO 3.1 to BI 4.1.
i am planning to follow incremental approach for reports ,universes and instances..etc by department wise.

what is the best approach to migrate users& groups and security rights??.

If i migrate all the users and groups first followed by report folders by department wise, will all the security rights exist for the users and groups  in BI 4.1  after the migration.

please let me know which is the best way for users migration.

Regards,

Divi.