i have a washburn idol, and it has buzz feiten tuning
http://www.buzzfeiten.com/

"How It Works
The Buzz Feiten Tuning System solves tuning and intonation problems with 2 simple steps:

1. Shelf Nut
Our exclusive Buzz Feiten Tuning System¨ (BFTS) Shelf Nut moves the strings closer to the first fret according to our Patented Formula. This eliminates sharp notes at the first three frets.

Buzz Feiten Tuning System Shelf Nut

BFTS Shelf Nut Top View Top View : Each Shelf Nut is precision machined from high quality bone for superb tonal response. Our Lightning Bolt Logo is machined into the top of each Shelf Nut for authenticity.

BFTS Shelf Nut Side ViewSide View : The strings are moved closer to the first fret a precise distance based on the scale length, fret width and string gauge of your guitar. The slight overhang of our nut (the 'Shelf') does this without altering your guitar in any way. So it's even fine for vintage guitars.

2. Intonation
Your guitar's bridge is adjusted according to our Patented Pitch Offsets, creating balanced intonation over the entire fingerboard - every fret - every string.

BridgeYour Bridge Is Adjusted to BFTS Pitch Offsets "

basically, it says that all of your guitars are set up wrong and mine is right.

i just dont get how if its so good its not universal yet.
is it just bullshit?

in my experience, its good for stuff like if i put my left hand on the 4th fret and tap on the 16th fret, it sounds as good as an open string tapping on the 12th, which i dont find to be the case normally.

so yeah, what are the negatives to this, cos i cant see them.