Are there really two independent pickups, or is it just a phase/wiring thing? For example, the Fishman Full Circle allows for two types of response by rotating the PU 90 degrees. I'm assuming that this results in either a phase shift or an actual difference in the pickup pattern. Regardless, it doesn't result in two separate signals. If the NS does have two independent pickups, then it might be possible to wire a blend circuit. On the NS basses with a separate magnetic pickup, you do have this type of wiring.