I bought the Cloud X to replace my old Clouds. Whilst I was initially concerned by the quality of the stitching, the shoes were very snug and comfortable nonetheless. After running my first half marathon in them, I was pleased to find that I had no blisters or soreness in my feet in the days following the run. The shoes felt like they put the spring in my step necessary to overcome the run's 1250m elevation gain. Once again, I'm very satisfied with my purchase of On runners (I've now had two pairs of Cloudsurfers, one Cloud and one Cloud X), and it's still my number one brand since 2013.