I haven't played a 2nd degree (though I want one), but I do have a NN and have had it in 4 different guitars. Right now I have mine in a neck-through super strat and it sounds killer in there. Maybe a WCR Icebucker would get you what you're looking for if you haven't tried one. I also have those loaded in my LP style guitar. I've also had the NN in that guitar as well too. While the pickups don't sound alike per se, I feel they both can serve in a similar capacity if that makes sense.
The NN & IB are both lower output pickups that hold together well under lots of gain, they track well, and they have some firmness under the pick attack. The NN has more lows and a rounder attack. The Icebucker has more glassiness to its tone and an edgier, more percussive attack. The NN is a little more open with not much gel/glue between the notes. The Icebucker has some good openness to it, but it also has a little more gel/glue. How I see their difference in openness play out is mainly in the way the pickups handle the low end with chunky, heavy gain riffing. The NN's work great with amps with a bit of compression and lots of preamp gain because of all their separation. With drier, more open amps, they can be a bit more challenging to get the low end to give the response most look for with power chords. The IB's seem to get that low chunk a little easier with the drier amps and they do well with amps with lots of compression and gain too. So yeah, the IB may be worth looking into since if seems you're into lower output pickups that hold together and track well under gain.
) and they absolutely destroy. They are the epitome of having a pickup that can do heavy but is still "clean". Lower output but great for Alice in Chains, etc. (not modern metal). I really dig them. My have a JB in my Charvel and the 2nd Degree Blackbelt sounds more organic but with less output. Still is awesome
