Would how the string is cradled in the metal change the tone? a shallow and loose v's deep and snug groove? the action height and intonnation even? I see where the variables can become almost immeasurable as Jon says, some guitars sound dark where the difference would be great some are naturally bright and it may be less. FWIW the graphite was so similar to a fretted low note that the difference, which
could be argued, but at the same time who has time. But I don't deny the
drastic differences for other esteemed brothers, as in a squier strat's plastic nut v's a brass one either, that sounds cool to me and would make sense.
FWIW, I am adding a brass nut to a guitar I am working on, strictly for the looks and maybe for the tone (who knows yet?), but through my life of playing around with my nuts, graphite has helped keep string slippage and catching during tuning much less than bone or my brass. I had one before that literally required lubrication to keep the strings playable in the grooves, again maybe a bad design (another variable!?

)
They look cool! and yes, especially scalloped. Does anyone have an idea where to get a scalloped one? I only saw raw, straight nuts on ebay.