I have no actual experience but have been reading up on high speed engraveing equipment lately. It depends on what kind of equipment he has and sepicifically the rpm's it works at. Some machine work at 400,000 + rpms and can engrave pretty much anything you could turn on the lathe. People use them to engrave wood, glass and metal includeing hardened knife blades. These high speed low torque systems should produce very little fuzzing and excel at small detail work as opposed to hoging out wood (what you want). To give you an idea a dremel runs about 35,000 RPM's on high.
That being said I agree with other definately give him a sample to try my only corcern would be melting on resin pens, but I doubt that would be a problem if he is careful, it is just the only thing I can think of that might be.