I had that same choice and made my bike out of neuron. Don't know how zona rides, but the elliptical butting made it a pain both to miter and weld. They basically have little tongue depressors of steel inside the top and down tubes in the butted section at the major stress axes (like on the top/bottom of the down tube where it hits the head tube).
It's definitely more complex than zona and the downtube is significantly lighter, but I can't tell you much about the ride difference. Oh, yeah, and I couldn't find neuron in oversize or megatubes, if that's important to ya....