I am sorry for being a bit redundant. I did make some inquiries into the durability of Teflon nut grooves. I got enough input (from BT & Wammi) that I am convinced the grooves will not wear lower. Thanx everyone! Now my Luther has raised some questions regarding timbre. He says Graph tech nuts give warmth to the sound, brass makes it metallic, & bone is kind of neutral in comparison, nice tone, resonance & sustain. (What he prefers, but he'll give me anything I want). I told him that once you put your finger down on the fret, the nut goes out of the equation. He says the nut still vibrates & contributes to the sound even w/the frets activated. I am pretty sold on the Graph Tech, it usually is recommended with my Kahler/Wammi bridge. But I have about one day to send the Graph tech nut back. Should I give my tech's advise (regarding tone & sustain) more consideration?. I could use a little more input, this stuff is new to me.