Clocked almost 500km rotating between the 3 shoes (Kiprun KD900x, Puma Deviate Nitro 2, Puma Velocity Nitro 3), running almost everyday for the past few months, some thoughts below. RunningThreads Kiprun KD900X: -Mostly used on faster workouts like sprints, thresholds and tempo runs -Very stiff, foam is very firm compared to other shoes -Runs like a brick on slower runs, less noticeable on faster runs -Needs good lockdown to get the most out of the shoe