Personally, I think that if one pays for a Microsoft Office 365 Enterprise level plan that you should get the Planner Pro version integrated with it. What's the point of just getting the basic Planner (that I would expect with an Outlook.com, Hotmail.com, or Live.com account). Seems a bit pointless to not have Planner Pro integrated with an Enterprise account, especially if an organization is unable to justify the expense of subscribing to Microsoft Project because its not integrated with the Enterprise level Office 365 plans.