I find that the migration wizard has moved the DHCP server to the Destination Server, but has failed to move leases and reservations and possibly other information. This causes IP conflict errors when the Destination Server hands out leases for IP's that are already leased to clients. Mitigated somewhen by enabling conflict detection on the DHCP scope.
The wizard has UNINSTALLED dhcp server from the Source Server, so I'm unable to complete the migration manually.