As I said, most of the problems are DNS related, and these are the most troubling in my case. But a few minor things were not so smooth as I was expecting... one database had migration problems, fixed when I manually exported/imported it; some configurations of the original Plesk weren't migrated... so I had to manually recreate the plans in the new server and then, manually, create the links between domains and plans. And so far we did only 12 of 49 domains. Well, let's see... I will try for a bit more because I still have "easy to migrate" domains. If they go smoothly I might conclude the migration with the sensitive domains I am leaving for the last batch.