I've just finished migrating all our schools over to 365 from various other providers. We have a single instance now, staff are really enjoying it. All our technicians are holding various training sessions, in the last couple of weeks we've started to make use of Skype for Business which is saving a tone of time instead of travelling to meetings.
The quickest way to migrate from one 365 tenant to another was using ediscovery to download all the PST mailboxes, i had to manually edit each one as they are downloaded into a "Primary Mailbox". After, i uploaded them to 365 and used the migration tools to import into the new mailboxes.
