So how would that type of CNS stress compare to say that same person bench pressing 6 x 2 above the 90th percentile?
Well the first type where open loop control movement initiation to exert maximal force, requires a great deal of coordination and control. I believe the effects are quite similiar since you are overiding reflex mechanisms. Comparatively speaking they are different, but I believe the end result is the same. Think of it this way, it's like comparing the neural fatigue of 100m racing to 400m racing. One is from attaining maximum control and coordination, the other is the result of trying to maintain that control and coordination while the rest of the body doesn't want to.