to make things even worse, the migration from AdobeID to FederatedID is not "just a change of the authentification". according to Manage identity types in Adobe enterprise offerings the Migratiion from AdobeID to FederatedID will basically create a completely new account and then try to migrate the assets to the new account. according to the doc this migration can be performed by the user automatically, but sone cases need manual migration.
I strongly recommend to reach out to ClientCare if you can migrate your users directly to FederatedID.
remark: be aware that some functions can not be accessed by FederatedID, for example this forum
Update on some issues we face: you are not able to migrate from old legacy login to FederatedID directly. that means, every user needs to be migrated to either AdobeID or FederatedID first.
If you want to change the accounts to FederatedID afterwards, you sinply contact CustomerCare and tell them which users should be migrated. After migration the user can login using SSO and everything works as before. he even keeps all elements (workspaces, segments, calculated metrics...)
bad news: the user gets an "entity selector" to choose between AdobeID and FederstedID. this is completely useless since only FederatedID will work (AdobeID is disabled due to manual migration). According to customer care this is "working as designed"... however has designed ...
result: no problems for migration excepts the useless "entity selector".
you can do whatever you want. If you have already setup FederatedID (and tested it...) I would suggest you move directly to FederatedID.
Be aware that when you first migrate to AdobeID, the user get's an email to set the new password (if he doesn't have an adobeID yet). And as soon as you disable the old login to anayltics, the user is forced to use the experience cloud login.
Therefore it is easier for your end users to directly move to FederatedID since all they need to know is the new login page...