Originally Posted by bluejack
I tried a helmet mirror for about a month, but I hated it
I had the same experience, but for different reasons. I found that it jiggled so much that it took several seconds of staring at it just to determine if anything was behind me, whereas a quick peripheral glance told me what I needed to know in less than a second. The mirror, for me, was more unsafe than no mirror. BTW, this is the Take-A-Look mirror.
I'm open to the idea that I wasn't using correctly, but I've had so few occassions where I was truly unsafe without a mirror, that my incentive to change my current methods is low.