I'll add that - regardless of the migration - if you have conversation history in the app which is valuable to you (it sounds like you have), do make sure you export backups (Settings->Backups) and put the resulting files somewhere safe (outside your phone). Also make sure you store your account password(s) securely somewhere, because they are required to decrypt the backup file if you need to access it in the future.
I'll add that - regardless of the migration - if you have conversation history in the app which is valuable to you (it sounds like you have), do make sure you export backups (Settings->Backups) and put the resulting files somewhere safe (outside your phone). Also make sure you store your account password(s) securely somewhere, because they are required to decrypt the backup file if you need to access it in the future.