As always -- we mean full-state migrations where meetings come over as real, update-able meetings with all attendees and resources, not just appointment slots in your calendar.
But our previous methods grew out of our first-generation technology using an external database (a legacy of our genesis migrating Meeting Maker).
Our new version reads Zimbra data directly without any intermediate steps or need for tunneling your MySQL ports. It has the advantages of being simpler and faster but still delivering full calendar migrations.
We'll have more to say about this in January but we've got it going reliably enough for us to tell you about it.