If you see somebody who looks like they are gonna run up and blink shotgun ya, just double jump yourself and get as high as you can, they won't be able to get you with the shotgun, just try it. And as far as people blinking away in the middle of a gunfight when they start losing, if they have time to stop shooting, jump, then blink away all while you're shooting them, well maybe you need to pick a better gun or place some better shots because they should be dead.