What I noticed in these tests is that after about 100 miles, the shoes lost negligible cushioning and energy return. The discussion says that, "KMT ran endurance tests on several shoes and stopped at 1,000 miles since it is unlikely anyone will run this far on a single pair." I would like to see the information on the next 500 miles before making any conclusions, but is the advice about replacing your shoes every 300-500 miles overrated or just untrue? Should you really just run in them until the uppers fall apart?