Integrating GMAIL with Zoho (IMAP VS. POP3) and advantages of just using Zoho Mail as Host

Integrating GMAIL with Zoho (IMAP VS. POP3) and advantages of just using Zoho Mail as Host

How is IMAP protocol working with Gmail?  I would like to understand the advantages of IMAP over POP3 (syncing across multiple platforms/devices) (Do you have to do IMAP protocol for each user etc.) (storage issues? cost?) What other issues are you seeing with using a third party hosted email programs?  

What are the advantages of just using Zoho Mail and the related cloud storage?