I have the hindsight and think they are just about right. They are big enought to give a decent view but small enough to be unobtrusive. If they were any smaller I think they would be difficult to use. I have yet to find a motorcycle mirror that gives a good view.
1. It's not concave, it's convex. A concave mirror is "caved-in" (rather than bulging in the middle) and would reduce the field of view.
2. The hindsight is also convex. As I said in a previous post, I don't know if the curvature is differrent since I've never seen a blindsight.