Hi Gee........I'm a strong proponent of a mirror - I've only used the helmet style, but it saved my life once. It took me 2 or 3 days to get used to it and to position it for easy use, but now it's so natural that I even find myself using it when grocery shopping.
I did find that the glue stick-on pad will gradually weaken and it will fall off. I took a long darning needle and pierced two thin holes thru the helmet foam and sewed the pad with fine wire to the helmet. I used a doubled up foil from the top of a Gatorade powder can as a washer on the inside of the helmet (I was on tour at the time). It works great. If the geek factor bothers it only takes a moment to pop the arm and mirror off the pad --- but then you can't look at the ladies behind you in the grocery store!