Fred tuned our piano recently. The piano has not been tuned for many years, since I am not a musical professional, so I had no idea how off the tunes were. Once he was all done, I used my Seiko STH100 Metronome/Tuner to check and 95% of the keys are right at the spot. Rest of 5% are extremely close and that would be my cheap $25 device margin error.
Fred is a very nice personal with a heart of a teacher, showed me how to clean the piano inside. Will use again.