WP Rocket versus Hummingbird, Thoughts?

Based on a site performance analysis here on my dashboard at wpmudev (less than a month ago) I did some research and decided to set up WP Rocket on several of my networks. I'm still within my 30 days with them, so can still back out now that we (wpmudev members) have Hummingbird flying. I've seen the recommendation that we make sure we have another caching plugin set up to assist Hummingbird, and that there are high performance free caching plugins from which to select for this purpose. I have two questions: 1) What specific settings/functions should I make sure I'm allowing Hummingbird to perform versus WP Rocket, and 2) Does WP Rocket have worthwhile value for me now that Hummingbird is included in my membership -- e.g., in what areas do you see a continued benefit to using WP Rocket, beyond the free caching plugin you otherwise recommend? Thanks!