I've run ultra marathons for 21 years, and have run mostly in Montrails the past 7 years. I bought my first pair of the Masai about 3 weeks ago. They felt damn near perfect! At that time I was finally coming out of my longest period of not running well in, well, since I started way back. Is it the shoes? Not just. Have they helped? Absolutely. Great grip. They absorb jolts from rocks and roots, respond quickly to all changes in terrain, dry quickly, and feel cool. They even look cool, especially covered with dirt, mud, whatever. And I thought I liked the Vitesse and Leone Divide! (Well, I did. But these Masai, for me and my feet, blow all those others away). Did I mention they fit me great. Run Amok!!!!