I run 4-5x a week training for a half marathon and open run mini is my best friend. Even at work, I always wear it for bg music. I don't have to worry about listening to music privately and at the same time being aware of my surroundings (we have a kid in the house so that's important).
OpenRun mini's fit is just right. Unless you have an extra huge head, the regular open run will be too large and dangle at the back of your head.
Cons:
I'm a musician, and the sound quality does not compare to most buds/headphones/earphones that you can get way cheaper on the market. But this isn't designed for that anyway so I don't really care.