7 rep
I send a lot of design proofs to clients for sign-off, and the feedback always comes back as an email that says "move the logo up a bit and the blue feels off." Then I'm guessing which logo, how much up, which blue. It's the worst part of my week.
What I want is for the client to open the proof and drop a comment pinned to the actual spot, "this headline" with a little marker on the headline. A read-and-comment mode I can share, where they can't edit but they can point. That one feature would save me a round of revisions on basically every job.