The blind spot mirrors (it had one each side) nearly got me killed so many times yesterdy that I pulled the mirrors in and relied on my neck joints to keep me alive on the way home. Needless to say, they are now sitting on my drive waiting for the car to drive over them.
I liked the concept, but they were really distracting, not only was I faced with two images, but trying to re-focus my eyes between the flat mirror and the convex ones just did my head in.
My blindspot mirrors are set so that when the image goes from "main", it appears in the other. I find them useful to keep an eye on cars trying to sneak up on you in traffic