We have completed a successful ‘lift and shift’ implementation using the ‘migrate to Launch’ functionality, and everything is working OK.
Am I safe to now simply swap the old DTM embed code with the Launch embed code?
Yes, If you want to swap DTM embed code with Launch directly at page level you can do that. Only make sure don't push any changes through DTM if the DTM property still in active mode after migration.
Better disabled that property after complete migration into Launch.
If all data can be collected normally, it can be replaced with launch.