Yeah, what are the pros and cons of a brass nut? I have a Spector NS-2000/Q5 and saw that the NS-2000/5 has a brass nut and got curious.
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Brass nuts are definitely more durable in the long run. On open notes, they allegedly sound brighter than other material.

However, the one bass I have that has one is finicky with the tuning. Don't know if its the bass or the nut that is the cause.
Brass nuts will probably enhance sustain, in another life many years ago our steel guitarist used a solid brass slide.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn