This Topic is really an interesting one !
I had a similar-ish question I put in one topic some time ago : The NB I tried didn't worked for me as well. It was too dark, too smooth, and not the "huge agressive assault" I was expecting from its description.
The RY, still alnico V, has to me far more presence and bite when I tried it in an SG type guitar. It was also tighter than the NB.
So I'd say now that the NB doesn't work in every guitar and doesn't match all tastes but on the other side it has that ability of being versatile while covering lots of music styles, from metal to blues, whereas the Crawler does it from blues to "metal" while being equally at ease in a strat or an LP, as it's description says...
That said, if your were looking for a passive humbucker to replace the EMG81 of your RR24, and expecting same kind of tightness and agressivity, you must - at least - stay with a Ceramic magnet. I think that ANY alnico V magnet will be too warm and loose for you.
There an exchange policy at BKP, see with Tim with you still can benefit from it and go with what he and the other here said before : The painkiller ! :twisted:
Also ask Antag about his clips of the PK in his KV2 and also ask Gwem about his choice to replace the EMG81 of his RR24.
Note that the Miracle Man would also be one stunning option for the RR24, maybe less agressive and present than the PK, but with *maybe* more balls and thickness on the chuggy-palm-mute-works !
Good luck ! :!