In our Free Social Edition we have enabled metrics that make sense to have in a dashboard. Engagement would be the most important one.
There are two big reasons to have Twitter Engagement metric on a live dashboard
To be successful in social media means having large audience of followers who are interested in your content. Engagement metrics tells you if people are interested. If they interact (engage) with your content it is a good thing. If you have Engagement metric in a dashboard you can see if the level of interest drops as it happens. You will have more time to fix a drop in interest if you identify it early and an online dashboard is perfect for that.
There is another reason to have Engagement in a real-time dashboard.