Grundignz:

 

You are correct i need to investigate the calendar side more

 

It was the extra calender's that get setup which if i understand correctly each one then becomes an extra mail box which would then run into $1000's/year more

Sounds like a slightly odd concept to me, but it might make sense if I saw it.

In case you were unaware, Exchange on Office 365 has a neat thing called a Shared Mailbox.  It's a fully functional mailbox (e.g. it can send and receive email and calendar requests) that you cannot log into directly, but can be attached to any other account to be viewed in Outlook.  It cannot be viewed on smartphones and tablets, except when you are using Webmail in a browser.  The cost, you might ask?  Free.  For us, when a client has a staff member depart, their paid mailbox is turned into a free shared mailbox with a couple of mouse clicks, and attached to their Manager's account (so the historical email appears below their own folders in Outlook).  This may be suitable, and I am unaware of any limits on the number of these shared mailboxes.

Not trying to give you the hard sell.  Just a possibility you could explore if you felt it worthwhile.

For Disaster Recovery purposes, having email in the cloud makes good sense for an SMB, even if it is slightly more expensive when costed out over 3 or 5 years.  SBS was brilliant and I remain a big fan, but after being very slow to come around I have become an evangelist for Exchange Online.  (It's a shame there's next to no money in it!)  Other Office 365 or Azure components I'm less in love with or on the fence about.