When moving to Dynatrace, your AppMon PW data will not be migrated. However you'll likely find that it does not have much value once you've moved to Dynatrace. For those customers who really want to keep that historical data available we suggest they keep an instance of AppMon running so they can access that history. But every customer who does this, soon realizes it's not necessary and deletes it. I'm sure you'd come to the same conclusion.
