I run a pretty consistent number of hours a week and tried the Vibram for a couple of days and know a couple of persons who once owned them. They are 'ok' for smooth pavement or any smooth running surface. They can probably be worn up to a max of half marathon but be ready for some serious hurt. Don't even try to wear them when trail running. I myself wouldn't wear them for longer than 10K run. I think its great for walking, brisk walking, or an easy pace run. Other than that, stick to minimalist shoes with thin soles.