Getting four or more people into a shot at once for an interview and maintaining the subject/background separation that makes interview shots so beautiful is a tall videography task. Controlling lighting on individual subjects is exponentially more difficult than framing up just a single person for an interview. Add to this the need to get the interviewer in shot too and now you have a 5-person mammoth of a shot.
The biggest benefit I see to owning a 4K-capable camera is being able to have two cameras in one when exporting to full HD resolution. What I mean by this is that one camera can give both a wide-angle shot and a cropped in close up shot without sacrificing HD quality.
In the case of the following band interview, this cropping benefit allowed me to get the wide shot of all five on-screen subjects while also allowing me to crop in on the person speaking at any point. This meant I could place this 4K camera on a tripod and not be worried about a lifeless still shot because I knew I had the freedom of adding zooms, pans, and slides in post-production. With the 4k camera stable on a tripod, my hands were free to hold a second more portable gimbal-stabilised camera to get the dynamic close ups that make one-subject interviews so eye-catching. So with the two possible shots of the 4K camera and the third dynamic shot of the handheld camera, I could maneuver the difficulties of such a large amount of interviewees with the knowledge of plenty of post-production shot freedom.
For a comparison to this five-person shot, I also filmed a short interview with just the lead singer of the band and interviewer. From this second interview you can see how much easier it is to control lighting and get lots of tasty close up shots.
The grand takeaway from all of this learning for me is that larger interviews require much more planning and trust in your equipment. You have to have faith that your equipment going to allow you the freedom to edit something dynamic together in post-production, as long as you plan and execute.