I'd like to share my thoughts on the Buzz Feiten Tuning System....
I have great respect for Buzz as a guitarist and I was excited when he came to visit me in late 1985 or early 1986. I do remember it was at my old shop at 33rd and Madison. I was already the leading guitar tech in NYC for improving tuning stability and intonation for the studio pros in town. After Buzz explained his system to me, I agreed to make two electric guitars and incorporate his "system".
Six months later the guitars were done and I invited several players I respect to play them and compare them to my regular guitars. The consensus of all the players was the difference, was at the most, "slight". My feeling at the time was if I was going to pay a license fee to use the system and promote it as an "improvement", the difference needed to be "smack in your face" obvious. It wasn't.
There are two main features of the Buzz Feiten tuning system. First, it involves moving the nut about .020" (twenty-one thousandths of an inch) closer to the first fret. This is to compensate for the increased stretch of the string, the closer you are to the nut. The stretching of the string drives the note sharp, so moving the nut closer to the first fret compensates for this. Regarding the nut location, this has been in the guitar building literature for 150 years.....so except for the fact that Feiten was the first to patent this, there is nothing new here. I have been incorporating this compensation into my guitars for the last 30 years. The second feature of the Feiten system is a set of offsets for intonating the guitar at the bridge. These offsets range from plus or minus 1 or 2 cents (a cent is 1/100th of a tone). The problem I have with this part of the equation is that I pretty much defy anyone to play a note 10 times in a row in 1-2 cent tolerances. How close your finger is to the fret, which finger tip you use, which part of the fingertip you use, how much finger pressure you use, etc, etc, etc, all contribute deviations greater than 1 to 2 cents. In addition, as your strings age, the intonation changes. And every time you change strings, let alone brands or gauges, all of this changes as well.
So with all repect to Buzz, I really think the system is one of "smoke and mirrors". If you have paid good money to have your instrument fitted with the Feiten System, you will hear the difference because you want to feel you got your money's worth. On a properly built instrument, with the nut cut at the right height and placed at the correct location, and a properly intonated instrument, I doubt if you will hear any difference at all.