When you say "mailboxes on any type of hold cannot be migrated", this would include any user mailboxes that are enabled for litigation hold? As, every user mailbox we have is enabled for it.
Most large companies will have their users on some form of litigation hold, so in order to migrate cross-tenant, you are asking us to remove that hold? When the next maintenance window runs all that expired hold data will be deleted right? If that's correct, surely no one will do this...
If the above it correct, this is a bit irrelevant in our case, but the migration is limited to 12 aux mailboxes. Are their plans to increase that? We have several that exceed that, however the mailboxes are on litigation hold.