Yeah it's very subtle.
SO subtle in fact, that the frets are NOT angled differently.
The Feiten system involves relocating the nut, adjusting the intonation (it has to be "off" by a certain amount), and following specific guidelines when tuning the guitar.
Korg makes a tuner that has the settings pre-programmed.
If the Feiten system involved angling the frets, it would probably cost more.
The current price for a retrofit is around $175, and there is no way that could include pulling off the fretboard, installing a new one, a full fret job, as well as moving the nut...
And Mr. Buzz Feiten also gets a little cut of that $175.
Thank God for patents!
And it costs around $400 to become a licensed Feiten retrofitter.