When you migrate from a hosted environment to another hosted environment, MigrationWiz is the most optimal solution because we, ourselves, are a hosted solution. This is very benefitial for you because you won’t be bottlenecked by bandwidth as you would be when you run your own tool on-premise (even though most likely you will be bottlenecked by worker throughout and not reach maximum bandwidth utilization).We’ve made some serious investments recently with regards to performance when migrating from Google Apps/Gmail to Exchange and BPOS. What does this mean to you? Easy, this means that an average mailbox of 1GB will now be migrated in a few hours. In fact, we’ve achieved well over 1.5GB/hour migrations to our own servers per mailbox. Note that your total throughput will be how many mailboxes you migrate at the same time. For example, if I migrated 100 mailboxes, we would be moving over 150GB/hour to our own servers. How’s that for speed?