In my book someone wearing Nike 4% shoes is no different from someone using EPO/other forms of blood doping. Both are cheating. And if you wear Nike 4% shoes, you are a d-bag. The difference is clear. Marathon world record before EPO got on the scene: 2:06:50. A decade later: 2:06:05. A difference of about 1%. The world record before cheater 4% shoes: 2:02:57. The record afterwards: 2:01:39. A difference of about 2%.