If you are planning to perform office 365 migration with native techniques then you may face following limitations.

Mailbox Size Limitations
Time Consuming
Down time
Reduced Productivity
Duplicate items creation

If you want to avoid all the above listed limitations then you need checkout our third party tool called EdbMails Office 365 migration which does your job efficiently without any data loss. It supports incremental migration which never creates duplicates on consecutive migrations and it has no mailbox size restrictions and it has zero downtime.

To know more Office 365 Migrate Mailbox | office 365 migration steps | office 365 migration Guide