My experience was very similar to another review from Paul. My intended use is for light to moderate trail running but specifically for cross-fit and working out. These shoes were exactly what I thought I was looking for: lightweight, great-comfortable sole with exceptional support. They even minimized and almost negated some long-term pain I've had in the balls of my feet, which my doctor has suggested to be early onset of arthritis. Due to this, I REALLY wanted these to work out. But, the lack of rigidity about the toe-box was too much to ignore. The toes collapsed and pinch enough to become a decent distraction during my exercise.
Ultimately I've returned the Cloud-X in exchange for the original Cloud. They have a bit more rigid upper especially at the toe. The Cloud is a slight bit more firm in the sole (only noticeable with one of each shoe on), but am hopeful they will soften up over time.