Charlie pointed out that Mo injured his achilles 1 week after getting that vary rigid signature spike.
I don’t know what exact spike they’re using, but I can say from using the Japan Lite-ning that it is as light as the old JSC (and quite a bit lighter than the Maxcat II), but it has a “monodensity” plate that is between the JSC and Powercat in terms of stiffness. I can see where they might be able to make a custom spike that is just as light, but with a plate that is as stiff as the Powercat.
It appears to me that the main contribution to Lemaitre is the biomechanical analysis and a custom shoe design to improve his claimed inefficiency. But the truth is that the Japan Lite-ning is so good that it makes Nike’s flagship sprint spikes feel like motion-control jogging trainers by comparison.