Right now, it shows diff between first arc diff and last arc diff. Comments from reviewers are lost in between. It would be nice if Differential pre-selected last diff with comments and last arc diff call. Either that, or highlight arc diff calls with review comments.

For example: D9140: Allow dashboard panels to detect rendering cycles and arrest stack overflows. Say @epriestley (author) or @btrahan (reviewer) opened the revision after @epriestley had sent the last arc diff. They would be most likely interested in viewing https://secure.phabricator.com/D9140?vs=21708&id=21727 rather than https://secure.phabricator.com/D9140. For everybody else, full diff should be fine.