I've taken a look at the Discussion Redesign in beta to see how the SpeedGrader view changes for the instructor. The Change Log for the Discussion/Announcements Redesign states:
"In SpeedGrader, the discussion view is updated to open directly in the iframe. Instructors view the entire discussion and the selected student’s earliest response is highlighted briefly."
I'm not sure why this specific view is changing. In the legacy/original view, when an instructor opens SpeedGrader, they can quickly see how many times the student has commented in the discussion board (both initial posts and replies to others). When I'm viewing the same discussion in Beta, I am brought to the initial post (sometimes; when I toggle to the next student I don't always see their intitial post if it falls "lower" in the discussion) and I have no idea how many times a student has replied. The only way I can see that information is to expand all replies in the entire discussion...this is not quick nor easy to assess in graded discussions. When in SpeedGrader, an instructor/grader is trying to assess a single student. There are times where they need to view the comment in context with the rest of the discussion...but that's not the case the majority of the time. Opening the entire discussion appears really distracting when trying to grade, when the original view nicely displayed all responses from the single student with a link to view that comment with full context.