Carth OR vs. NS, solid counter or just dumb luck?

NS with zNest standing in for acolyte is what I'm seeing the most of these days. I use geos for those. Double zeta brood, mostly g12. It's a little dicey in the beginning with stuns, but i can usually clear the ns in 1:30-2 minutes. Then it's just a matter of getting the timing right to one-shot nest with spy.