My specific example 

I use a Group for my superusers where I post things only relevant to them (updates, feedback requests, etc) and where they can ask questions / share thoughts about their superuser experience, etc. 

I’d like to increase engagement via a Dynamic Content widget that shows for them on the home page, increasing visibility and awareness. 

The Dynamic Content widget respects permissions, not showing for users who don’t have permissions to that category. So if it worked for Groups, it’d be perfect for this use case. 

In the interim, I considering switching to a category. But if/when I do, I’ll lose these advantages Groups have over Categories:

• Featured content has a more modern tile/card UI than the featured content of categories
• Group member listing on the side promotes sense of community, belonging, etc and awareness/connectivity with others in the group
• Joining a group auto-subscribes you to email notifications (and then you can turn them off while remaining in the group, if you’d like). Whereas community categories require an opt-in subscription action by each user with no way for Admins to force/apply an opt-in for them. 
  • This is the biggest one. I used the Group because I want the default to be that superusers get email notifications when I post in the group.