Based on your survey responses , we recommend that you set up Office 365 mail services using a Minimal Hybrid mailbox migration. ...

Based on your survey responses, we recommend that you set up Office 365 mail services using a Minimal Hybrid mailbox migration.  A Minimal Hybrid migration is similar to an Exchange hybrid deployment in that mailboxes are moved from an on-premises Exchange 2010 or Exchange 2013 organization to Office 365 using the Mailbox Replication Proxy Service (MRSProxy).  Like an Exchange cutover migration, a Minimal Hybrid is intended for Exchange organizations that want move quickly. However, unlike a cutover migration, it does not have a 2,000 mailbox migration limit and you can migrate Exchange Archive mailboxes. Minimal Hybrid simply turns on enough components to allow mailox migration to work.