I have both. For me, the Crux is earlier and stronger overall. I pull out the Crux on medium-heavy to heavy patterns. The Zero Gravity gets easy length and produces a smooth but very strong backend on medium patterns. I definitely think there is room for both within the same arsenal. I think the Zero Gravity is right next to benchmark in terms of reaction. Compared to my IQ Tour Solid, it's cleaner up front and stronger/more continuous down the lane on the same conditions.