Yeah that machine is awesome. Su is definitely someone to study as far as joining lifting and speed work. I feel like with attempting to make lifts specific its pretty hit or miss, maybe some of the criteria for specificity are met really well while others are so far from the movement its use becomes really limited. And understanding and applying the structural change component is pretty tough as well.
But I think the upper 1/8 of a squat is potentially so difficult to maximally overload, the leverage is so good, that for an elite speed athlete, maybe even a leg press would be maxed out before approaching overloading the 1/8 RoM. In my mind thats the potential magic of a very well set up variation of this lift - tension generated earlier in the lift, but max force having to be applied at the very top due to the bar bounce no longer assisting at that RoM. But even if my theory is right, getting the loading and height correct, mastering technique and having to probably make adjustments to avoid injury, more likely than not it would be pretty impractical.