Switching between Yammer and Outlook in Office 365 Groups is not possible

At the Microsoft Ignite 2016 conference, Adrienne Trudeau, Senior Product Manager for Yammer at Microsoft, confirmed that an Office 365 Group will not allow you to swap between Yammer and Outlook in the group

So how can I choose which one I have in my group?
This is thankfully really simple:

• If your group was initially created in Yammer, then it will come with a Yammer group, but not Outlook persistent conversation (it will still come with a distribution list)
  
• If you create  your group anywhere else in 365, including in the admin portal, then your group will be give an Outlook persistent conversation experience and no Yammer group