If you’re already using the new app and comfortable with how your location is behaving, don’t bother with the migration. The migration tool does four things: 1) prompts you to migrate to a Samsung account login (the new app won’t accept SmartThings logins due to the permissioning backend), 2) migrates your routines to automations and scenes, 3) migrates any SHM settings to STHM and clears out the old version of SHM so you don’t get phantom alarms and 4) migrates any Lock Code Management settings to SmartLock Guest Access (if it’s available in your country).