I, too, am using that workaround and experiencing the "Sorry—something is broken" message before all individual student messages load. It's definitely quicker than the "Speed"-Grader, but considerably slower than the previous design.
Yes, I can imagine they received feedback from a certain class of users who may have endorsed this change. However, for those of us who diligently read the entire message board during the posting period, toggling through the entire discussion thread to get to individual posts is unnecessarily time-consuming.
You are certainly conscientious for contacting support (for which we all all benefit); and I will likely send a half-hearted email. Unfortunately, though, my faith in the power of the people to effect positive change is somewhat shaken of late.