I bought my Hollowbody Spruce used, and the previous owner had put in a PRS adjustable bridge (great!) and also a Tusq nut. I've been wrestling with the intonation a bit lately, especially on the low E string. It took me too long to realize the nut was the culprit. Last week I put the original nut back on (luckily in the case when I bought the guitar), and problem solved. Moral: don't mess with perfection.