| As good as you make it. If your intention is to alter the spacings or correct a flaw in the original in spacing or depth / height, then you certainly would be happy with the result IF you take you time and use the correct tools & technique.
If you are looking for substantial differences in tonality, sustain, etc - then you may be quite disappointed. Years ago brass was common for the use in this context . The idea was that it would provide more sustain. Yet comparisons showed it really didn't. Brass DOES have an advantage in the it's very strong, doesn't crack, & takes a slower sweep of a file (more strokes) to accomplish the same depth as softer material. This makes mistakes less likely as it demands more time and concentration (generally - people can screw up most anything in reality).
Bone cuts quickly and demands a good sample to get consistent density. Graphite is consistent but cuts fairly fast so care is demanded. But in reality the actual SOUND will not vary to such a degree than many people expect.
There have been several articles over the years in many magazines where tests were done on this specific issue and the results appear to be on the level of construction rather than resultant sound differentiation. | 
