A couple of users will get the Office 365 Business Premium, others will get just the basic Exchange only plan. Those with the Premium will get an up-to-date new install of outlook. On the other, what will we need to do to get older versions of outlook to switch from the SBS server to the O365?
Two issues here – first moving the email, second setting up Outlook
Do all users have Outlook 2010 or higher – if so you should be able to add the O365 account to the profile, shift the email and then disconnect the SBS account
Alternatively, do an export to PST, remove the profile, and create a new one for O365, then reimport from PST
IMHO treat this as an opportunity to get users to clean up their email (like the Duchess, said more in hope than anticipation)
and do yourself a favor and pull the keys for your old office installs that get replaced on the Premium stations. it will come in handy if you have that one station using the pirated copy of Office 2003 Enterprise in the janitor closet… you can get the entire key for 2010 via a multitude of key finder apps. sometimes people see the totals and assume that you are going to move the 2010 instance over for them…