I tried an early version years ago, and it was alright. Not for rookies though, I had a customer who was way off on his tuning, and the machine tried to tune it to the right note, wrong octave. Goodbye string.
@JackDaneCPA: I can tune by ear but some stuff like Radiohead, they just have some strange tunings. This would allow me to play some things I have always struggled tuning and also put it back on standard tuning easily. 4951