You only need large quantities of pDNS data for the discovery portion. For classification all you need are collections of domains produced by the same algorithm ( which are readily available for the widely-known DGAs.) The domains being NX isn't so much corroboration as fundament -- the NX-producing search over multiple domains is the observable behavioral distinction between AGD vs static C&C discovery.

(I've worked with both Antonakakis and Yadav, and implemented the production version of Damballa's AGD classifier as per Antonakakis).